Game.co.uk are selling the DualShock 3 controller for £24.99 when its bought with anything else.
The cheapest item you can get is a DVD wrap for 99p. Combine both to get the controller for £25.98
Or if you buy something to bring the total to over £30 you can use the £3 off £30 voucher as well.
I bought a £10 gift voucher and the controller for £31.99