My teenage daughter has asked Santa for a pair of these for Christmas. I've told her it's a bad i-deer (sorry! couldn't resist that one) because we live in the countryside and they'll stay 'Truly White' for approx 5 minutes... but, nevertheless, the cheapest I can find a pair is at House of Frazer - down from £51.99 to £41.59. As I live nowhere near a House of Frazer store, so I'd have to pay postage of £3.99 to get them to me, making them £45.09. HOWEVER - they hardly have any sizes left!
Hope this helps someone! <3