There is no better way to get started in robotics that building and experimenting with your own robots. The DiddyBorg Raspberry Pi Robot comes with everything you need to get started. It has 6 motors, a laser cut 3mm cast acrylic perspex chassis, and other components.
This kit works wit the Raspberry Pi model B or model B+. It supports the Raspberry Pi camera too. You can use the software to get the robot to auto follow and perform other tasks. More info is available here.