I know Morrisons have had this on offer for the same price recently, and Asda even had it a few quid cheaper. But these deals have been a bit hit or miss depended on store stock.
Game station are selling this for £20 across all three formats and they had absolutly LOADS for sale in their Banbury store. I was also told this was a nationwide deals also.
They have a lot of stock there are trying to clear and are offloadign it cheaply.
They also have the pre-owed copies for £24 :p