Like others said above, just make sure the seller you are buying from has a good feedback number. Check out the, say, last 20-30 items that person has sold and you can kind of gauge by that.
If they only sell a bunch of 1-2 dollar items to boost there feedback rating, and have never sold a Wii before(or any other consoles for that matter) then
I would avoid them. Go with somebody that has a ebay store. It's more secure.
Just do you homework before you drop 300-400 bucks on an ebay item.