Much as I hate to promote them Ebuyer have the Asus Xonar D2 7.1 PCI Sound Card for £89.99. This is going by all the reviews I have read a superb soundcard. The next cheapest price I have found is about £10 more.
They also have:
The Asus Xonar D1 7.1 Soundcard - PCI Connection with £10 off at £59.99 http://www.ebuyer.com/product/149266
The Asus Xonar D2X 7.1 PCI-E Sound Card with £14.99 off at £104.99 http://www.ebuyer.com/product/141346
The Asus Xonar DX 7.1 PCI-Express Soundcard with £5 off at £59.99 http://www.ebuyer.com/product/146350
Their usual prices on these are very competitive, with the reductions I can't find cheaper.