What if i buy a Samsung Exclaim at Radioshack with out the Pcs account?

I want to buy a samsung exclaim at radio shack. It's 29.99 with a PCS account but what if i don't have one then how much will it cost? And also i want to buy it like a little bit and little instead of buying the whole thing in one day. What's that called?What if i buy a Samsung Exclaim at Radioshack with out the Pcs account??