Just picked a pair of these AKG430 headphones from Staples in Sheffield for £19.50. They had 2 pairs in store in their audio section. No sign that they were clearance or special offer, just on the shelf ticketed up the same as the rest of the stock. No idea if this just a local deal or national.
Amazon currently selling them for £44.00 and John Lewis £49.50. Haven't tried them out yet so can't comment on how good they are, but get decent reviews on Amazon. Can't find them on the Staples web site, so in store only.
Also had a pair of AKG 512's on sale for £14, but they are too big for my needs