Borderlands 2 for £12 (~$17.99) from GamesPlanet
Just got the email then, this is the best (non-russian, non-pricing-error) price I think I've seen to get this game. I'll definitely recommend it - I've already had so much fun playing. I also found it kinda cool that Google converted the £12 price to a number you'd legitimately see on something, not a whacked out $16.81 or whatever. Anyway, enjoy!
The site says the end date is the 17th, but I marked as the 18th because of the time zone difference. The deal will likely end before this site says it will. Also, there's limited stock and the deal may end earlier still.