Seeking Advice - Pay-as-you-go / Pre-pay Plans (USA)

Hey guys,

Sorry if this has already been posted, but I (like many others I am sure) have been getting sick of paying $100+ a month for my iPhone via AT&T. I am thinking about opting out of contracts and buying my next phone outright / unlocked.

What possibilities are out there?

Ideally it would be someone with LTE coverage... My next phone will either be the iPhone 5 or a Win8 phone, and I am assuming they will both have LTE modems.

As a side note, I travel internationally quite a bit so Verizon is out for me.

Is this sort of thing even feasible in the U.S.?

Thanks in advance.