So I decided to build a 3d printer. I have been pouring over the RepRap documentation, and settled on the idea of building a RepStrap "seedling" based on recycled flat bed scanner parts.
I happened to be looking around a Hard OFF and found two identical scanners, perfect for X and Y axis.
I peeked down inside, and saw that they were belt driven by a geared down stepper motor. This should give a lot of torque, and higher resolution printing, at the expense of speed.
Also, they have a guide shaft on one side, and sit on a metal guide bar on the far end.