How much will an iPhone and it's data plan cost?

Ok so I want to buy an iPhone 4 or 4s. I don't think I'm eligible for an upgrade until some time next year. I do not currently have a data plan. How much roughly would it cost for me to buy an iPhone get it activated and add the data plan? Then how much is the data plan per month? (unlimited)

It really depends Where you are getting it from and what iphone you are getting

Who do you have? I have att and if you want to upgrade before you're eligible then you have to pay the full price of the phone+activation fee+ +tax+data. Full price is at least 200 I'd say for the 4. Activation is 30-40. Tax is 32 something (as of Thursday when my mom upgraded). And data 3 GB is$30 5 GB is $50. I don't know if they have unlimited but you can imagine how expensive it would be. But you really don't need unlimited it's excessive. You'd have to never close out your apps and be constantly on the Internet to go over the 5 GB one I think.