I was in Asda Living/Home store at Broughton Park (Near Chester) and COD World at war was "on sale" for £20. Shelves were full, at least 15 - 20 copies in there at 5pm last night.
Had a quick scan on find-games.co.uk and couldn't see it for that price anywhere.
Shopto - £34.99
I only saw it at a glance so don't know when it expires & unsure if it's in other stores nationwide etc.