I need a little help from a veteran cell user, looking at an unlock iphone

[LeglessTable]

i have been looking to upgrade my phone, i have a trac phone that barely works now. i really like the interface of apple's devices, i have an ipod touch, and it seems that every other phone on the market that has a large enough storage space for my needs requires you to get a contract with a specific company to get the model with the larger storage space. i want one thing in my pocket, something to act as a phone, camera, and music player. the iphone seems like the best fit for that, but i cannot afford those expensive contracts of almost a hundred bucks a month, so i have been looking at an unlocked iphone. i want a pay as you go model, and i think that i want verizon, but this is where i need help, i know nothing about cell providers or cell phones in general, since a basic trac phone is always what i could afford.
My question is, is it possible to get a true pay as you go decent provider, verizon or otherwise, with an unlocked iphone?

i looked the verizon website and it seemed from what i gather that you still pay monthly for the pay as you go, which is ok since i pay yearly for trac phone on top of the minutes i use, but it seems if i remember it was about 15 a month which is quite expensive compared to trac phone, considering that payment only goes into keeping your number active and doesn't contribute to the minutes.
i know i probably sounded like a babbling moron, but that only because i am please, a little help would be greatly appreciated.