Saw the Extreme 3D Pro in the Staples store in Telford, (Location at end) dont think you can get them cheaper, especially as online most stores are around £25 excluding any postage. 2 left on shelf in the Telford store yesterday.
The Attack 3's were also stocked (3 left) for £9.99, seems cheap compared to other places as well...
Logitech Extreme 3D Pro Twist Handle Joystick - £14.68
Logitech Attack 3 Joystick- £9.99 (w/o VAT reduction)
Also on display (just incase you want to know of their stock ^^) they had 2 Logitech G11's, for £24.47, this was mentioned in another deal thread so i'm not going to stick it in the title.
Unit 2, Rampart Way, TF3 4AS
(IN-STORE ONLY, not sure bout whether other stores have them, but likely they do ^^)