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.
Raspberry Pi 3
You might be able to use a Raspberry Pi Zero W instead of a full size Raspberry Pi, but I personally haven't tried.
RasPiRobot Board v3
Most any microSD card will do. You might be able to get away with a 4GB card, but I got 8GB ones instead. If you plan on storing lots of images or video on the card you’ll want a bigger one. I’ve used class 2 or 4 cards successfully, but higher class cards should be faster.
You can also use a USB camera. You would just need to find one that is compatible with Raspberry Pis.
This is a pack of 5. If you’re going to get more than one they are cheaper per unit this way. But if you just need one you can probably find just one for cheaper.
The 5 pack of range finders come with some jumper wires, but not enough for all of them. Single range finders may or may not come with jumper wires. If you don’t want to plug the range finder straight into the RasPiRobot board you’ll need kind of wires.
These are also handy if you want to add additional components to the GPIO pins on the Raspberry Pi.
These are useful for the nuts on the Devastator robot chassis. Other robot chassis might need different tools. This is a pack of 3. If you only need one you can probably find just that for cheaper.
Having one of these is nice to make sure the different voltages you think should be getting to different places actually are getting to those places. You can definitely get higher quality (and higher prices) multimeters, but this one seems to work.
The Devastator robot chassis comes with a battery holder that holds 6 AA batteries. This ones holds 8 AA batteries to help your robot last longer. It also has a cover and an on/off switch.