You mean the phone? I think that the cost is not so much, but naturally for me!!
What about my phone? I bought a launch-day Sprint 4S... Can I just go to another country and pop in my sim? How does this work?
Apple factory unlocked Iphone's costs;
Iphone 4 - 8gb (black only) - $549
Iphone 4S - 16gb - $649
Iphone 4S -32gb - $749
Iphone 4S - 64gb - $849
Yes, you will be able to use it on any gsm carrier.
you should have no problems, I've done it already