It's official: the US is in the grip of Wii Fit fever. And it's overriding some people's common sense. Consider this: as of today, copies of Wii Fit are selling for $US 130-$US 170 on eBay, even though the game will be out on store shelves in the States tomorrow. And will retail for $US 90. Shame it won't exercise brains like it does your balance.