These are the wheels we are running for 2012. They are $4 from Harbor Freight and are used for wagons and hand trucks. Using a 26 tooth sprocket from the kop, a CNC Plasma cutter, and some TIG welding we were able to mount the sprocket to allow us to drive the wheel with standard parts.
The mount is a piece of 3/16 steel that is cut, then drilled and tapped, and welded to the steel rim. We use two hubs that have the extension for a two sprocket wheel placing one sprocket on each side of the wheel.