If you're attempting to teach people on FRC programming, a FRC drive test board is really the best way to go. You could get some basic programming done with a Raspberry Pi or Arduino controlling a simple little robot kit that you can find from a variety of sources. Get a cheap little educational kit from amazon and you could easily cannibalize the motors and chassis with an Arduino to get it up running quite cheaply. A simple little board with some basic gearboxes (we use
Andymark CIMple boxes) and a simple pneumatic system with a few pistons.