Cell Phone Plans

[RxZ]

Maybe my GoogleFu is weak, but I am having a hard time finding the answer...

We all know that the large mobile network companies (ATT&T, Verizon, etc) subsidize the cost of cell phones through increased rates on the actual plans. I currently have AT&T, and am eligible to upgrade to a new phone/plan which I want to do. However, what if I want to buy my own phone somewhere, and not from AT&T? Do they offer the same plans at a reduced cost since I would have nothing that needs to be subsidized? Or am I forced to go the pre-paid route (which after looking at AT&T's website is actually more expensive per GB of data)?

Or do I wait until the first of May 2013 when my two year contract is up, and say bye-bye to AT&T? But then what?

Thanks for any advice.