As per the title... Asda have a Wii bundle which gives standard Wii and Wii Fit Plus (inc Board) for £177. I've seen the post for the Wii Fit Plus at Asda, but didn't spot any mention of the multibuy discount.
The console on its own is £135.29 and the Wii Fit Plus is £69.71... buy both and you get a £28 multibuy saving. i.e. £177.
Seemed like quite a good deal to me. I know it doesn't get you the MotionPlus, but the best similar deal I found elsewhere was Play's for £229.99 (a Black Wii). Since Sports Resort (with MotionPlus) is only £35 (or less), Asda seems like a better deal.
Don't mind being proven wrong, though!
EDIT: should have said that this was at Asda Methyr Tydfil
EDIT: added scan of receipt (at least, the important bit). I also got an extra controller and nunchuk for £41, which is why the total is £218.
EDIT: Direct link to receipt http://i896.photobucket.com/albums/ac168/mushgussie/asda_wii_receipt.jpg