Some time ago I bought my set of
Callaway X14 on Ebay and I've been very happy with them. They were almost new and I paid about $240, this is when they were still selling for over $500.
I first went into the golf shop and checked out what I wanted (I know this isn't fair), then I went on ebay to see if any sellers had what I wanted for a good price.
Just ask the seller a lot of question. And pick a seller that has a lot of good feedback and deals mostly in golf equipment. There should be some sellers on ebay that are in the UK I would think.