I too have recently been considering getting goods from the good old US of A instead of rip-off Britain. However I had read elsewhere that you can get clobbered with additional costs by HM Revenue & Customs. To find out how much I phoned the HMRC helpline and spoke to a helpful chap. He explained that everything being imported into the UK, which is valued at less than £290, is subject to Customs Duty of 3.7%. In addition it will be subject to Import VAT the rate of which depends on the goods being imported. Apparantly everything has a 10 digit classification code, details of which are buried in the bowels of the HMRC website, but he said if you really want to know the Import VAT rate, then phone the HMRC Classification Team on 01702-366077 and they will tell you the rate for your waders, boots, rod or whatever. He also advised that after all that, the company processing your parcel when it arrives in the UK, eg Royal Mail, Parcelforce or whoever, should charge £8 Mail Clearance fee. So, in a nutshell:
Take your USA vendors price
Add the relevant USA State Sales Tax
Add Postage costs
Convert into Pounds Sterling, and if it's under £290
Add 3.5% Customs Duty
Add Import VAT (from HMRC Classifiaction Team. Alternatively add 17.5% - I think that's the max. rate ??)
Add £8 Mail Clearance fee
and if the total is less than you'd pay in the UK, seriously consider going for it
Of course the total figure you arrive at is a worst case scenario. It appears to be a bit of a lottery as to whether or not you will be clobbered with the additional costs at the UK end - just don't bank on being one of the lucky ones to avoid them.
After all that I forgot to ask the chap what happens if your goods are worth more than £290 when they arrive in the UK !!
Hope the above is accurate - if not, blame the bloke on the HMRC helpline