Some excellent prices over at HMV in their 80% off sale - E.g.
Firefly series - £10.99
West Wing Series 1 - £7.99
Hellraiser Puzzle Box - £10.99
X-men trilogy - £13.99 (excellent price)
Indiana Jones: Trilogy - £14.99
The Fly Ultimate edition - £21.99
See the forum thread for the links to these!
Probably lots more! I've just bought firefly, been wanting it for ages. Don't forget the 10% quidco cashback as well. Click the "Go to deal" button to browse. Please post any great offers you find :)