Let's say you really, really want a Wii U for Christmas. Problem is, it's pretty tough getting hold of a pre-order, because most places are sold out. What options are you left with?
Two. The first is to suck it up and spend the holidays without a Wii U. The second is to take to eBay and/or Amazon, where savvy assholes and re-sellers are more than happy to get you a Wii U. For a price.
At time of writing there are several Wii U consoles, some with game bundles and some without, going for over $1000 on eBay. Even funnier, shipping on some of these consoles can be priced at $200+. For shipping. It had better get to my house on a procession of elephants sounding trumpets for that kind of fee.
(For reference, the Wii U's retail prices are $299 (standard) and $349 (deluxe) respectively in the US.)
That's the price being asked, though. As for what people are willing to pay, things are a little more reasonable (relatively), with the highest bid on a Wii U auction currently at $465 for the deluxe console, a mark-up of only $116, which isn't too bad.
For now. I'd imagine things will get even crazier once Christmas inches closer and loved ones become more desperate.