I had bought DS the playmobil dragons castle for Christmas from John Lewis, which cost £59.95 - I found it last week at costco for £35 so bought it and the JL one will go back!
My sister had bought him the starwars millenium falcon transformer set and paid £29.95 which I picked up at costco for £11. So she's taking hers back too! In fact that was such a good price that I've bought a couple for the present cupboard.
That is a ridiculous saving - it just goes to show that it really is worth shopping around!