I want to buy an iphone 4s but I don't know anything about them and I don't want to get ripped off?

I found someone selling an iPhone 4s and he says it has Automatic Gevey. Can someone explain to me what that is? I'm currently living in Romania and my carrier is Orange. He said it has Automatic Gevey preferably with Orange. What does that mean? I told him I'm going back to America and would like to know where the phone was bought or what country it is coded so I know what to do with the unlocking and stuff. All he said back was that it's from England and Vodafone carrier. He also stated it has the newest software, ios 7.1.1, is it the newest? Sorry lol… I'm a total iPhone noob, I always had Androids. I'm just very anxious because my friend bought a 3GS apparently from the US from at&t and it was jailbroken I guess? He reset it and it didn't work after that and I really don't want something like this happening.

Some, maybe all iPhone 4$ are free here or very cheap. They had a promo at Verizon for 1$ I was in a pawnshop one day and guy came in with one and they said not interested.

Automatic Gevey is unlock software to make the phone available to work on any network. See the vid below. 7.1.1 is very new but you should be concerned about iCloud Activation lock in iOS7. If the old owner has an iCloud account in it, it will not be usable by anyone else. There must be no iCloud Activation lock or you should get another phone elsewhere. Best luck.
http://support.apple.com/.../kb/HT5818