Well your looking at a rare item. When demand is very high and the supply chain is very low. Wholesalers tend to boost the prices up very high to make extra profits on the item.
The Wii right now is close to impossible to get your hands on. I would not doubt seeing the Wii run up to $600 plus on ebay around christmas.
No matter where you go when the Wii becomes avaliable theres about 30 Ebayers racing to that store to buy that item. Some even camp outside the store for days to get thier hands on the small amount of units that come avaliable.