Can I buy an iPhone in the US and use it in another country?

So a sister of mine lives in Colorado, and for black Friday might be buying me an iPhone 5S or 5C, and mailing it to me in Mexico. I don't really care if it's locked, as for now I'll only be using it as an iPod touch until I go back to the US in a few months. I would go for the newest iPod touch, but it's slow compared to the newer iPhones. So Id rather get a 5S for the same price with better features.
I don't want to get it unlocked as either iPhones would be too expensive, and I won't be using it as a phone here. But I'm not quite sure what can be done about the contract, whether there's a way around that, and not having to pay for it. Since it would be pointless for my sister or I to pay each month, if the phone won't work here.
Hope someone can answer my question ^^ And also, no I won't buy an iPhone here. They're just too expensive.

You can only use it in mexico if it is unlocked! The sad part is that it will be more expensive!

If it's unlocked you can use any micro sim card from almost any provider.

If it's locked, you can pay to get it unlocked.

If you're only using it on Wi-Fi in Mexico, it really makes no difference if it's locked to a carrier. You won't be using a network so no need to even think about it. But when you decide to go back to the US, you will be limited to the carrier it's locked with unless again you pay to get it unlocked.

Why don't you just buy the Google Nexus5 for $349? It's unlocked, has amazing specs and a great screen. Then when you get to the US, the iPhone 6 will be out lol

Yes, you can use it and since you are using it like an iPod like hadget, forget calling, messaging in it. Everything else would run good.

It won't work outside the US if it is locked to a carrier. And only the carrier can truly unlock the phone and odds are they will say no. Or have you pay a very expensive cancellation fee.

You can use it anywher if unlocked. I have friends that use theirs when they go back to India, they put a local sim card in it there for local calling.

Yeah. But better change the sim of another company in the country you go.