the reason people bid so much is that they want those cash bonuses. it works out well for you if you actually get one of them, but don't win the auction, so you don't have to pay anything, but you get some money (or in other cases, a lot of money). the seller makes the amounts of the cash bonuses just enough so people make tons of money, but no matter what the auction ends at, he will be on top.
and who knows what the fuck is in the box.