I am thinking about getting one of the HOn30 Minitrains sets.  Where (US address) is a good plae to source them?

How hard is it to swap their couplers for Microtrains ones?

The minitrains will represent an industrial railroad interchanging with the Great North Central (The merger of the Sandy Rover and Rangely Lakes with the Wiscasset, Waterville, and Farmington.  Amazing how railroads that small (2 feet wide) get such long names!