As seen on TV in those gross adverts!
This is £9.99 on JML Direct and a similar price at their usual instore stockists (Boots, Wilkinson, Robert Dyas etc). If you need one and you're willing to wait a couple of weeks for shipping from Hong Kong, DealExtreme are doing them for $3.23, i.e. £2.26 delivered.
The pictures don't show the box so the item may not come retail packed, but not really a problem unless you're buying as a gift ;)