S.T.A.L.K.E.R. Shadow of Chernobyl (PC) is available instore at Morrisons for £5.99.
Not sure if this is all stores but it was alongside all of their budget PC games so well worth a look for if your doing a shop.
Pretty good game, worth a go for £5.99 i reckon.
Next best online price seems to be Zavvi for £8.00.