You can find my pseudo setup script here.
You can get other (including cheaper) robot chassis. The RasPiRobot board can drive 2 motors, so any chassis that has two compatible motors should work. You just need to know what voltage the motors take. The motors on this chassis are 6 volts, which is a common voltage for small motors like this. The max input voltage for the RasPiRobot board is 12 volts, so you probably can’t drive motors that are a higher voltage than that.