Build robots with my nephew

My nephew is interested in robots. I told him that we could build a robot together and he got really excited. Originally my plan was to get Lego mindstorms, but considering it is $350. I am hoping to find a cheaper way to test out the waters. Also, at his current age I assume he will want to keep what we build and may be a bit rough with it. I figure when he is a bit older Lego mindstorms is the way to go.

Anyone know of simple and fun robot kits?

• Nephew just turned 6
• Looking for something we can put together
• Simple action like pushing a button to cause the robot to drive forward for X seconds
• Looking to build something my newphew could keep and play with.

If anyone has any ideas shoot me an email, comment, or tweet.

Thanks! Current ideas (shared, sent, and found)

• makeymakey //thanks @Marchdoe
• smallest solar power car kit
• solar race car kit
• tin can robot
• owi 14-in-1 robot kit

Results

I ended up going with, the tin can robot. Which worked out great. Since he is 6 and the product is recommended for 8 and up, it was a lot more of me putting it together and him helping, but it did maintain his interest the entire time and we were able to finish the robot. I did have issues screwing nearly all of the joints together. I gave up on a number of them and ended up just taping a few pieces together with invisible tape. Overall, still worked out great, he learned some things it sparked his interest, and he asked great questions.