I managed to bag myself a complete season 1 of Battlestar Galactica Boxset for £12.99 at Virgin Megastore on Stevenage yesterday. There were several dotted around the shop with different prices (£17.99 and £49.99) but the bulk near the counters were all labled at £12.99.
According to the Virgin Website, the cost is £17.99 - however, they certainly had at least 10 others labled at £12.99.
Not sure if this is Nationwide - but enjoy if you want it and can get it.