I found this in Tesco Homeplus in Staines and can't be certain if it's available nationwide. It's still at £14.97 online (that's where the link goes) and had no price on the shelf but scanned in at £4.99.
It installed fine and is being used right now - a bargain if you have a notebook with a PCMCIA slot. There were about 8 left on the shelf.
There were also some Micradigital Wireless Cable/DSL Routers on clearance at only £11.97 .