I also have several used ones. Havent had the chance to hook them up. You can use any brushed or brushless motors that fits the specs. I have gotten two teknic brand motors off ebay. Also have bought some of the cheap servos and some ebay renco 500 ppr encoders, but they are waiting to be assembled.
http://www.cnczone.com/forums/showth...t=cheap+servos
Do you plan to make the cables for the motors and encoders as shown in the manual?