Spent a good chunk of money today on the project. I ordered a 20 mm linear ball bearing assembly from VXB for about $88 including shipping, which includes a 55 inch shaft, two slide units and two shaft supports. I ordered a IG32P 265 RPM motor and a wiring kit from Super Droid Robots for about $42 including shipping. I ordered a 4 ft rack gear and two pinion gears (2”, 1.25” diameter) from McMaster Carr for about $82 including shipping.
Still need a power supply, aluminum pieces to build the cart, and a control system. Also need a way to keep the cables from flopping around when the cart moves.