I love ebay but greedy ebayers really nark me. Don't be ripped off and pay around £100 for Wii fit on ebay.
Theres a site that checks a LOAD of major retailers every 60 seconds for stock of Wii Fit. At Christmas time I found a Wii console through this site, and I recently bought Wii Fit with the help of this site - took me one morning of having the page open on my desktop, and found one from Amazon (who incidentally seem to get stock every day - they just sell out quickly! )
I'm not allowed to post a link to this site, but google search 'find stock wii fit' and it'll be top of the search results, wii-consoles dot co dot uk