Normal prices are;
FIFA 11 £29.85
PES 2011 £21.86
There are 2 vouchers available at the moment. You can only use them one time each.
£3 off MS-EXPERT-XMAS Thanks to hsg
£3 off MCMEXPOST Thanks to Reser
As long as you haven't used the vouchers already they should both add to your account, thus allowing you to get the above two tiles for the cheaper price.
The vouchers aren't restricted to these 2 games but i feel these two offer the best value.
For those having trouble, you have to register and/or log in first. Then at the bottom of the page, click "redeem code".