Can i buy an iphone 5 without an upgrade OR paying full price?

Me and my brother are on my moms plan and there are no more upgrades to cross with(we have at&t). I upgraded a few months ago but you see, what had happened was, something happened and now i'm back to a 3gs. So i was wondering is there a way to get the 5 without needing an upgrade or having to pay full price?

No. You either need the upgrade, or to pay full price. Those are the only two options.