How much does an old iphone cost?

I'm 17 and thinking of just buying one of the old iphones because I heard it's a lot cheaper (?).
And any store example would be great.

Depends on which of the older models you are talking about. The iPhone, iPhone 3G & iPhone 3GS are no longer made or sold by Apple so the prices would depend on who sells them.

The iPhone 4, iPhone 4S & iPhone 5 are the ones still made & sold by Apple.
The 4 is free, 4S is $99 & 5 is $199, 299, 399 on a 2 year contract.

If you are wanting to buy them off contract, ebay or craigslist is your best bet. The first gen is under $75, 3G is under $125, 3Gs is under $175, iPhone 4 is under $250, 4s is under $375, and iPhone 5 will be quite expensive.