If I could choose one thing...

I'd say cheap acrylic paints and a few brushes.  Practice with washes for fading and grime.  Probably the biggest game changer for me.  

-Matt

+1 for acrylic craft paint washes

Yup. Matt’s got it. Definitely the way to try weathering on a shoe string budget. Shopping list:

1. numerous bottles of craft paint from Michaels /Hobby lobby etc. on sale less than a buck each. Burnt sienna, raw umber, off white, maybe some grays and charcoal (not pure) black depending on your subject. 
2. joes budget thinner recipe or armor all window cleaner works nicely. 
3. dull cote spray to give the car a little tooth so the wash doesn't slide off and seal the finished product with same
4. cheap variety pack of brushes. 

Your in business for less than 20 clams. Raid your recycle bin for small containers to mix washes. You can dry brush trucks and paint wheel faces with the same paints.  Later on get some oils and pan pastels if you like.  

HAVE FUN!

jeff

+2 for craft paints

Wal-Mart seems to have the cheapest prices 2 for $1 but my store always seems to be out of colors... 

While your there (or at your local thrift store) buy a hair dryer. 

Complete list; 

Craft paints

Hairdryer

Tap water.

But once you buy them they last forever. I would say use tap water to make washes as that's "free". If you airbrush, then Joe's thinner is useful. I tend to make a gallon at a time, but I rarely use it for washes.

The other thing I would say is prototype photos for reference. Its easy to over do.

For 20 bucks you could have a lifetime of weathering fun.

Wet water wash?

Craig my experience with straight tap water for acrylic washes has been mixed... sometimes good but sometimes it beads up or sheets. Worth a shot though!

for 99 cents

use a gallon of distilled water instead of the tap water. It's well worth the $.

anything I really need?

 practice, practice, practice! Get some of the paints recommended and some old cars you don't mind messing up and start experimenting. Should be plenty of online videos and info to help you decide what works best for you....DaveB

Suggestions

I’d suggest you start with chalks (pastels) over craft paints.  The chalks are more forgiving if you’re a novice.  You need a set of “earth tones” for most weathering.  You can get a set of 12 for about $10 at an art store or WalMart.  Here’s a set on Amazon:
Earth tone chalks

Powder the chalks and dust them on.  Or, streak them on using plain old rubbing alcohol. Here’s an MRH article about how to do it:
Weathering with chalk and alcohol

There was also a good article in 2011 all about weathering but with an emphasis on using watercolor pencils (you can get those for about $1 a piece...a couple tan colors, a light gray and maybe a white).  There’s a video explanation along with the article:
Weathering with watercolor pencils
 

There are supply lists in both articles.  Both of these methods will get you going for probably $20.

Hope that helps. Good luck!
Bill
 

India Ink

Be sure to grab a bottle of india ink. Washes of india ink is one of my mainstays for weathering. Pretty much everything gets a wash of this stuff.

All these are great! I also

All these are great! I also like the Pan Pastel. A little costly up front but certainly goes a long way. Also, to give a flat finish try Krylon 1311 available at Michaels for about $11 but they have a %40 coupon either by print or on your smart phobe.

Jeff

Good advice! A couple questions remain, though...

I read that article and thought it was interested, but I thought they recommended water-soluble water pencils, which might be more expensive than $1.  Maybe I'm wrong.

Lots of good advice!  I'll go over this with my dad before proceeding.  He says he's pretty sure he has the India Ink and I'm pretty sure brushes won't be a problem (unless I destroyed them all already).  Maybe he has a few of the other items on this list.  Lots of good supplies and techniques are listed above.  I just have one more question... what about the Chalk Ink Pads I mentioned in the origional post?  Any particular reason why I as a beginner should steer clear of them and why much do they cost?

one more thought

My first "fade" attempt was very poor.....lots of spotting and little particles that destroyed the illusion. One of the factors was impurities in the tap water (hence the suggestion above) but the biggest issue was the old boxcar that was sacrificed. It had been laying around so long that it was dirty. Hey! I'm going to do weathering....a little dirt won't hurt! Fail.

 Wash the car before starting the fade. Also, probably mentioned above, but you'll need a can of Dullcote.

Learn one method at a time

Stick with one method to start. Its really easy to try a whole bunch of things at once (and fun) but you'll have a hard time improving because you can't follow and understand how the weathering works.

Personally, I would stick with the craft paints. Cheap, easy to make washes, fades, etc. Once you get these techniques down then you can try things like chalk and pan pastels. Since you are on a limited budget, you'll get more bang for your buck with craft paints vs other stuff. Say you spend $20 on craft paints at 50,cents a piece, that's 40 different colors vs buying a set of pan pastels (20 colors on Amazon) for $75. 

Last weathering job I did in 1/29, I used maybe 10 colors total and the black color (not a true black but off black) had maybe a 1/8" of paint gone from the bottle. Check out some of the weathering projects over at "The Rustbucket" forum. Guys are doing incredible weathering jobs with acrylic craft paints and using maybe 10-15 different colors.

A lot of great tutorials like this one.

https://tws-rustbucket.com/thread/3556/color-transition-fades-acrylic-paints

Final thoughts

First off- you should tell us your first name ( makes it easier to say “Hey Pete” as opposed to “Hey DRGW 488 Fan”) It might also be helpful to know exactly what you are weathering for your first attempt (a structure? a boxcar? locomotive?) I did find some watercolor pencils for about $1, but hold off on those for now. The methods discussed in that article include chalks and still worth reading.

I’m completely unfamiliar with the “chalk ink pads” so I couldn’t offer an opinion.

Alcohol and India ink was recommended to you on the other page. (A/I is what you’ll see a lot of modelers call it).  Primarily, an alcohol/India ink wash instantly adds a film which “ages” the piece being weathered so that the colors aren’t so stark. I keep a couple bottles on hand to age raw wood. You just “paint” it on and when the alcohol dries, you’re left with the aged effect. I wanted to mention that getting the correct type of India ink is really important. You want non-waterproof ink.  NOT waterproof.

(Here comes the boring technical explanation...The reason to use non-waterproof ink is because it gets mixed with rubbing alcohol. Rubbing alcohol contains 10-20% water. But, if you use waterproof ink...the ink will “fight” the water component in the alcohol. That means it won’t go into solution correctly)

The brand I use is Higgins non-waterproof ink.

Specifically,  Higgins #44021
It’s also called fountain pen ink   Higgins Black Non-Waterproof Fountain Pen Ink
A pint of isopropyl alcohol (rubbing alcohol) should cost $1 at the drug store.

You mix 1 tsp into a pint of rubbing alcohol and shake it up.  You’ll have a lifetime supply of A/I weathering solution!

I would still direct you toward using pastel chalks for your first attempt. Follow the advice in either of those articles (and search “chalk weathering” on MRH) and dive in! This horizontal boiler was weather using nothing but chalks:

Here are a couple more... It took years of practice and experimenting, but I used only chalks to create the weathering effects:

 

I hope all of our advice isn’t too overwhelming! Get your supplies rounded up, start weathering and post some pictures of your results.

Good luck!
Bill

Remembered one more thing today...

In addition to acrylic paints for washes I'd pick up a bag of  Cosmetic Wedge.  Get just a bit of paint on them and then press most of it off onto a paper tower.  The remaining paint can be lightly applied in a random fashion to simulate dirt and rust.  

Finally my favorite resource for modeling on the cheap, including weathering can be found here: 

Modeling railroad can, but doesn't have to, be expensive!

-Matt 

Charcoal

Start off weathering with chalk pastels and charcoal, they are very forgiving. I use charcoal to bring out detail. It brings out depth in grills, door seams etc.  unless you seal it with dull coat it will rub off on the flat surfaces but most things that I use it on don’t get handled. If you over do it you can remove it pretty easy. The photo shows what the charcoal highlights.  I just brush it on with a cosmetic brush and blow off the excess. The trucks in the photo have not been dullcoated. The one on the left is right out of the package, the one on the right charcoal dusting only. It works great on freight cars as well as the grills on a locomotive. I have had the same jar for over 20 years as it goes a long way. Nothing goes on my layout without weathering, 

Richard 

Not any more ...

Prices are going up thanks to the pandemic and IPA being a major ingredient in hand sanitizer. If you hurry, you might find a cheap bottle still, but prices online have already gone up to the $10+ range per bottle.

Here's a lab source that shows a pint of lab-quality IPA now at $16 a bottle:
https://www.laballey.com/products/isopropyl-70-500ml-16-ipa-rubbing-alcohol-isopropanol-2-propanol-for-antiseptic-first-aid

And the price gouging has started on eBay (I dare you to find a bottle of IPA on eBay for less than $10):
https://www.ebay.com/b/isopropyl-alcohol/bn_7024810643

India ink is too limiting

I find India ink for making a wash to be too limiting. At about $2-$3 per oz, it's no cheaper than model paint. Also, I don't use turps and oil paint for this either.

A huge one is that I can get an “any color needed” wash using model paint. An India ink wash is worthless on dark colors. There, a wash made with a light tan model paint (coffee & cream color) works a lot better.

Other benefits to using a water-based model paint, acrylic thinner, and flow enhancer to make a wash over alcohol and India ink (or turps and oil paint) ...

1. I don’t need more supplies ... India ink, alcohol, I can use the same acrylic paint and thinner I use for everything else with just one new supply: Jet Dry as a flow enhancer.
2. I can literally make the wash any color I need. For example, I can make a light brown “coffee and cream” wash to use on a black car or loco.
3. The wash now “spreads” along the details, seams, and grills similar to the India ink and alcohol wash.
4. No strong smell of alcohol, yet it dries quickly, unlike an oil and turp wash.

Too limiting

While I agree in part with the limitations of alcohol & India ink, the original poster admits to having no weathering experience. A/I would be an easy way to try weathering for the first time. 
 

I should’ve known the price of isopropyl alcohol would be spiking. $10 per pint is medical grade IPA (99%) I’m still able to find the 70% rubbing alcohol variety for around $2.50 at my neighborhood CVS and Walgreens. Although I see some online retailers are indicating “out of stock” or “in store only.”  

Learning curve

First you must know, to have a good weathered effect this take some learning curve and time.

Since 45 years I use only water soluble products for all my paint job including weathering for all my N scale models

I just would say the only expensive thing I use are first quality brush.

This mean the use of acrilycs paint but also water colors and course pastel chalk and the now used Pan pastels colors.

In fact my weathering effect are a mix of all these products together

They are added in thin wash, wash over wash.

All the paint are thinned with distilled water and isopropilc alcohol.

I also use distilled and alcohol water with natural pigments or even with pastel chalk or pan pastel

I use as darker wash only india ink and isopropyl alcohol; I use Georges Sellios mix, one tea spoon of india ink and one pint of alcohol; the FSM aged look come only from this wash.

The result obtained are very easy to use and can be augmented if necessary.

Charcoal powder is also an excellent substitues to add coal spout and grime on cars and steam locomotive.

I also use some kit paint from MIG and AK colours which offer some special effect kit paint very useful and so easy to use for special effect of rust, natural metallic shine, dirt, the list is long check their line.

About the india ink wash, some say is not the way to go or it could give to dark effect; you can mix the soap with more alcohol for your special need.

For wood, it exist some colored ink which can easily mixed with isopropilyc alcohol to give more colored effect too.

One rule is to use very light wash and come again and again to accentue the wash to the desired effect.

Cheap acrilics paint and some artist one are the basic colours, chalk powder is inexpensive, like natural pigments; a visit in a artist supplier store is the best way to go to find everything you need.

Like already mentioned, the india ink need to be from a good quality and non waterproof.

This wood N scale scratch build structure, was paint with Golden artist acrylics colors.

The rust effect were obtained with touch of rust colors, touched up with pastel chalk, pigments and pan pastel, some brushed with water; the humidity bottom line was obtained by dry brushing green and black pigments; the whole structures was brushed with the india ink mix, drybrush of white was also added.

In fact nothing out of reach for sure.

Acrylic alternative to Dull Cote

I use this mix instead of Dull Cote because I spray in my basement

1 part Liquitex Flow Aid (diluted per their instructions)
1 part Liquitex Airbrush Medium
4 parts Golden Matte Polymer Varnish w/UVLS

This combination drys matte flat and can be brushed or sprayed

Cheers,

George

Like Craig said..........

I'd highly recommend joining the RUSTBUCKET forum.  It is not very active these days but that doesnt matter for what you need.   There is  plenty of tutorials and how to write ups and photos.  Plus just going through past projects from some of the best modelers around.  It's all weathering, with an emphasis and realism.  You will find many more modern techniques and products than on a typical general model railroad forum.  Although it is mainly trains there are also vehicles and structures.    

Weathering doesnt need to be expensive.  What will help the most is using a prototype picture and copying it, this avoids the "fantasy" look.  Slow down, take your time.  Practice. Start simple and work your way up.  Youi will find the products and techniques that work for you.  Use what works for you then.  What looks good is more important than what or how a product is used.

Also check out other modeling groups especially military modelers.  Model railroading tends to behind lagging behind compared to aircraft and armor modelers.

Good luck and share your projects.

Steve

weathering

DRGW,  Because of my handicap ( I have hand tremors ) I can't draw a straight line to save my life. So I discovered a different way to weather. I use Sharpies and 91% alcohol. I just put a spot or dab wherever I need it and then spray a fine mist or just a drop or two of alcohol and let it run down. Gravity still works. If you are willing to experiment a bit it can be easily mastered. I would recommend the two finest tips they make fine and ultra fine each in black brown and gray to start. Some sort of misting bottle as fine a spray as you can get ( I use empty eyeglass wash bottles ) and some alcohol and your ready to start. A word of caution- the alcohol may make the paint turn chalky. It can be rubbed off or used as a fade. Don't be afraid to play with it and have fun! I also really like Pan Pastels but they are a bit pricey for just starting out. Oh and the Sharpies are permanent, so no need to seal with Dullcote after or if you don't like what you did just spray on more alcohol until it's gone. Good luck!  Kodachrome John

Wow!

I don’t know if this shopping list is having the desired effect for our “rookie weatherer”, but I can tell you that I’m certainly getting new ideas and motivation from this thread!
(Dullcote alternative, powdered charcoal, Sharpies + alcohol...all tools I need to try or revisit.)

And...I finally got myself registered on the RUSTBUCKET forum (thank you Steve & Craig for the kick in the pants I needed!).

Bill

@Bill

It’s not as active as it used to be Bill but it still has all the content.  Well worth it for anybody serious about prototypical weathering.  Glad you joined, maybe some more will too and give it a shot in the arm. 
 

steve