The Hut are selling "Fifa 08" for the Sony PS3 and Nintendo Wii for £17.93, and for the Nintendo Ds, Sony PSP, Sony PS2 and PC for £12.93 (inc Del.).
You can get cashback through the usual sites (e.g. 5% Quidco)
The next best prices are PS3 = £28.99 (ChoicesUK), Wii - £27.99 (PowerPlay Direct), DS = £16.49 (PowerPlay Direct), PSP = £16.99 (PowerPlay Direct), PC = £14.95 ShopTo, PS2 = £14.99 ShopTo.