There is no better way to learn electronics and robotics by creating your own gadgets and playing with them. The Zumo Robot is a simple kit for Arduino with two motors to drive its treads. It has a 0.036″-thick laser-cut stainless steel sumo blade on the front to move objects around. The Zumo has sensors to detect lines and avoid edges.
You are going to need Arduino or a compatible control board to get started. More information is available here.