The GBP is worth so much compared to the dollar, you should just buy your games from U.S. sellers online and pay the little extra for shipping. If you buy a lot with a few games to consolidate on shipping, you'll really make out like a bandit.
Troll around the forums for a bit and wait for a sale, and if not, I guess ebay gives you some options (though it is hated by many for gouging). Your currency valuation will basically cancel out any gouging that can occur.