Popped into my local Morrisons this morning, and they were only just putting out the sale stock - which is where these deals are, not with the main chart stuff. The guy let me have a look at the boxes he had but said the games weren't arriving until later in the day.
So I went and nabbed the last £39.99 Portal 2 from the chart section as I figured the prices were all centralised, and low and behold it scanned at £7
The checkout lady looked a touch confused, then just said 'well done', and off I went.