US banks tend to lead the pack in novel ways to change more fees. My parents purchased tickets through British Airways, priced in USD, and their bank hit them with a 3% fee. It's totally made up. There's no extra fee to the bank in processing a dollar transaction down the street vs. one processed by BA in London. That being said, it's rare in the US for these kinds of foreign transaction fee, and there's plenty of cards with no fees at all for any currency.

For the OP, why not just pay the local currency? Paying in your home currency is almost always a bad idea when traveling - it's usually 4-5% or more these places tack on when they're being ever so helpful and offering you to pay in pounds.

There's plenty of UK cards that offer no transaction fees:
http://www.money.co.uk/credit-cards/...ction-fees.htm