Series 8 will be relased on dvd on 26th December 2006 (strange date, so it could well be changed) at a price of £31.99
A bumper boxset of seasons 1 -4 (the best seasons of the show in most people's opinion) is released on dvd on 9th October 2006 at a price of £69.99 (shop around as I've seen it priced a lot more than this!)