[ctccromer]

It depends on the materials you already have. I've seen both 1 and 2 wheeled shooters that work pretty well. Here's what my team did:
Essentially, a flat surface (sheet metal, plywood, etc) with two cim's on the left side (one in the midpoint and one at the end) and pneumatic wheels attached to the cim's. Then at the bottom of the surface, we put a window motor and bent some angle aluminum to serve as an arm to push frisbees into the wheels.
As for HOLDING the frisbees, we went to home depot and got a 5gallon bucket and mutilated (read: cut) it to fit our design needs. So if you already have the motors, this could be a cheap option for you, and it's been VERY effective for us. If you're interested, check out my signature