S.H.
Look on E-bay.
Just enter "robots" in the search box.
Boys... they can break anything!
I have a boy.
Something else that is fun/cool: "HexBugs." My son and daughter like those. It is a micro bug robot.
Look at Amazon for it and just to read the reviews.
E-bay has it too.
Also if you just do a search on Amazon for "robots" many will come up and you can read the reviews there of the products.