I just saw that The Electronic Goldmine has the Faulhaber gearhead motors with built in encoders sold "As Is" for $2.95 (regular $11.95) because the ribon cable may have cuts in it and some motors may not work properly. Still, for the price of a pair at a regular price you get 4 pairs of motors to use in several projects, so I thought I should share. I've used these motors in my MiniEric robot and I'm very happy with them. Use the Pololu wheels (3mm D shaft) or the 3mm wheel hubs for easy wheel mounting. Review of the motors here.