Was looking around various websites to see if any online store had Wii Fit in stock... well I haven't managed to find anywhere yet!
Anyways, found that tescos direct appear to have the best offer (but please tell if there is better).
Wii Fit - Tesco.Direct
Not only is it £64.71, but you can get extra money off possibily with quidco and also tesco clubcard points. Have not looked into it too much though, but you can collect from certain stores and get it delivered (not sure how much the latter is).
Anyways... hope someone will find this useful, and hope someone can beat this offer lol.
PS (Attached vouchers may work, I have not tried)