Can I get an iphone aboard and use it in my own country?

I'm travelling to USA. And i might buy an iphone over there because its cheaper. Problem is, i'm not sure whether its still working the same in my country. Well, the sim card and network is not a problem, i will use my own one once i reach my country. But i'm still worrying if there are any difference of what?

Just buy one from home

According to my knowledge there won't be much a problem. You will just have to change the location settings, etc

It shouldn't be an issue as long as you buy the phone outright, obviously you can't buy it on contract price.