[Kevin Sevcik]

I think your best bet would be to use a standard motor and some micro switches. It'd take a little careful wiring. The basic idea is that you have a switch to run the motor in one direction or another. Once you have this wired, you put a micro switch in the middle of one of the wires for one direction on the common and normally closed terminals. Then when the switch is hit, the motor stops turning in that direction. It will still turn in the opposite direction when the switch is flipped.

"But Kevin," you say, "I want it to make multiple revolutions before stopping. How can I do that with microswitches?" Well now. It's possible and done every day. The trick is to base your motion off a screw getting turned by the motor. Then put a nut on it or something that will get moved back and forth and have that trigger the microswitches. Adjust the stop positions by moving the micro switches forwards and backwards.

Now. This method does take a bit of mechanical finesse and possibly some machining. On the other hand, encoders and stepper motors need a control system watching them constantly.