ROB the Robot was a peripheral that released alongside the Nintendo Entertainment System in America because NOA (Nintendo of America) feared that citizens of the United States wouldn’t buy a game console, but would love to buy toys. Therefore they created this peripheral to pack-in with a deluxe version of the system. It could only be used with a few games, the one that most people know of is called Gyromite, a so-so stack-the-pieces-just-right game.
While 100% complete packages of ROB (with Gyromite and all the knick knacks) goes for about $350-$400 on ebay, I only have ROB himself. But even in his incomplete state he can sell for around 150 big ones, easy. I’d say the 2 bucks I spent on this little guy was quite a smart investment, wouldn’t you?