i-phone compatibility

hello everybody, i'm a user from Greece.
So i have a problem about buying an i-phone device because here these devices are very expensive and i would like to ask if i can buy an i-phone from the official site of apple which are less expensive and their price in US$ or i will face any problem?
thank you

You'll want to purchase the phone from Apple Greece page here. I imagine once you do that, the prices will be the same as to wherever else you are looking..

i would like to order an i-phone from apple usa or else i'm thinking of buying an i-phone from an american site so i can earn more money from the money transfer (from US$ to €).