What are the specs of the motor Does it have an encoder, or a tacho? Brush type, under 80V 20A with an encoder? If so you could use a gecko G320 to drive it. If you are or have access to someone with a bit of a bent for electronics, it shouldn't be hard to make a up a little circuit which outputs X step pulses each time a button is pushed.
Then you just need to make up a simple DC power supply, for which there are instructions on the Geckdrive.com site.
You could scrounge an old pentium 1 computor, install free dos, and use turboCNC with a very simple program to command the gecko if you don't want to make a dedicated circuit.
That will cost nothing if you are a good scrounger, but take up more space.