This super simple balancing robot project looks pretty easy to build. It uses an accelerometer to provide motor data. An Arduino Uno controls it all. If your like me, I bet you could salvage most of the parts from the old bottomless closet.
It looks like there is plenty of room for improvement, maybe a wireless remote or some sensors to provide information to the Arduino about how to control the robot. But overall, this would be a good platform to get started in self balancing robots, motor control and accelerometers. Code for the Arduino is provided!