Its all about currency exchange and extra taxations in different countries.
You can always grab a redeye or a standby by going to the airport, come to the US for a 1-2 days vacation for cheap since part of the cost would be the difference, buy the phone, walk around and eat some burgers and apple pie then get back over the pond. lol
Haha sadly it would cost me a lot more than £140 to come to the US from the UK.
Thankfully should I ever want to buy an iPhone from the US my cousin works two weeks in the UK and two in the U.S. And Asia. All his apple stuff is from Asia or the US as its so much cheaper. His MacBook cost him almost £400 less than buying at home. So I do have the option. I just worry about warranty being world wide etc (local Apple Store told me it's not).