I dont have a iPhone but i know they are extremely expensive. Thats up to you if you wanna do that i dont think i would ever buy something like that for so much.
I bought the 32 gig white iPhone 3G S the day it came out for $300, then the plan is whatever you want +$30 a month for the plan that gives you internet and everything. Now that doesn't include text or calls, so that's the "whatever" part that you have to pay.