I've ordered many things from the UK before direct from Amazon and other places... never had to pay import duties
I placed a pre-order though HMV they're only charging 4.50 GBP to ship "Air Mail" I'm assuming that's regular post and it will take a few weeks. the only other option was "Overseas Currier" for 37GBP... so yeah airmail is fine
maybe I'm wrong but I don't think the US has import tariffs like other countries do.
the state I live in has no sales tax at all... so I don't see why they would charge one to import goods.