Red Dwarf series are available from Virgin Megastores site for £6.99 (free delivery). The list price for each series from a general search comes out as £10.00, but if you click on a specific series and add it to your basket the price drops to £6.99 - I do not know if this is a mistake or not!
Grab them while you can - these are usually cheap at double the price. Good one for early Christmas shoppers!
Sorry, don't know how to add a pic.