I picked up the Sumo-Bot Robotics kit for $30 at CompUSA. My son loves it, and it has real learning potential vs the Robosapien he got for Christmas. This is a small wheeled vehicle with control electronics based on the Basic Stamp 2. Manuals on disk guide assembly and teach electronics, robotics, and programming.
I should mention, a 9-pin M-F serial cable (not a null modem cable) is required to connect the robot to your computer.

