Getting down to necessities of life, in the UK you pay a massive mark-up on US-made guitars. A threefold markup isn't uncommon (I've seen $600 Martins for £1200!), and paying double the US price would be normal. I don't know who's making the money here. Some of it is doubtless down to import taxes and shipping, but nowhere near all of it. I don't think this is the manufacturers - I personally suspect UK guitar shops are ripping off their customers. Ditto guitar strings.
But on other things, US-based companies have simply set out to fleece the rest of the world. CDs, DVDs, clothing, cars - all of these are sold for artificially inflated prices in the UK. Cars are getting better (after a crack-down by the government), but luxury items are just getting more expensive. We've basically stopped buying CDs except for birthdays, because they're too expensive to buy on impulse.