I would like to ask a stupid question.. I'm technology stupid 
Is it not possible for those in the UK/Europe to buy an Iphone from say, Ebay from the USA? Because with the difference in currency, they are SO much cheaper (about $400 difference) over there! Is there any kind of "lock" to prevent this? Any info is welcome

Is it not possible for those in the UK/Europe to buy an Iphone from say, Ebay from the USA? Because with the difference in currency, they are SO much cheaper (about $400 difference) over there! Is there any kind of "lock" to prevent this? Any info is welcome
