RASPBERRY PI
The Raspberry Pi is a very powerful Linux computer that's not much bigger than a credit card. Plug it into a TV or monitor and a keyboard and you have a fully-functional computer. It's simple enough for education projects, yet has enough horsepower for serious applications.
Buy any qualifying Raspberry Pi kit valued $49.99 & up and get the Make: Raspberry Pi-brary PDF bundle for 70% off. Use code baked314, must add both items to cart to qualify.