Go to this site -
Wii Fit £69.99 - In Stock Locator Click on auto alerts. You have to leave the tab open and it refreshes itself every 60 seconds, and when there is stock you get an alert or a fog horn sound goes off. You have to be quick though.
BTW, i got my Wii Fit from here after a few days and i also managed to order my friend one a day later, so it can be done.