It cost thirty bucks. My students (who wrote their first computer program last semester) had it up and running within the first hour after it was delivered. Two weeks later and they have a wifi controlled skid-steer robot prototype running using the Rasp. Pi, Arduino, some proprietary motor controllers, a PS3 controller and PyGame. Now they are refining their code/design, improving it. They spend so much time working/playing with it, that they are slacking off in their Communication Theory coursework. What a tragedy.