If I bought a used iPhone of of eBay, would AT&T automatically start charging me on a contract?

I wanna get a iPhone without mobile network, so I don't have to pay for a data plan. I just wanna be able to call and connect to Wi-Fi? How would I do this without spending $450 on Apple.com?

You can buy a used iPhone off e-bay or craig's list and use it as if it were an iPad. You would only be able to make 911 calls unless you got it activated with a carrier. If you do'nt want to spend a lot of money on cell service, look into one of the prepaid providers (I think Ting uses the AT&T network).

You can't. Any smart phone that is connected to a phone carrier charges for mobile usage even if it isn't used. You can't get it just for Wi-Fi it doesn't work that way.

You need to connect to a carrier to make calls

I get that, i will pay for calling plan, but would I HAVE to get a data plan?