They seem to be a commercial version of the breed known as BEAM robots. Here are some BEAM robots I made. If you modified these to use a small solar engine, they would be full-fledged BEAM robots.
HexBugs come in five shapes and colors and cost about $16 USD each. Shown here is the HexBug Bravo Green. You can also buy a Complete set of 5 of these micro-robotic insects for $50 USD.