Meet the Makeblock mBot Ranger: a STEM robot with a transformable design that can be turned into a robot tank, three-wheeled racing car, and self-balancing 2 wheeled vehicle. It comes with a visual programming interface. You can control these robots from your iPad, other tablets, and laptops.
The robot is based on the Arduino Mega 2560 with 5 sensors and 10 extension ports. Costs $189.99 at this time.