No, you don't have to.
There are tens of thousands of iPhones right now with AT&T GoPhone SIMs....
I think I can live with 250MB of 3G data per month. With AT&T's cheapest postpaid iPhone data plan, you get 250MB of data at $15 per month. With GoPhone, you can buy a 500GB data package for $25 which will last thirty days. ...
Total two month cost: $30 for 510MB of data, which is actually cheaper than the postpaid plan.
Calls are ten cents a minute. I average about 30 minutes of talk time on my current dumb phone (on a T-Mobile Pay As You Go SIM).
Wow. I thought I was joking about TracFone.
Well, at this point, you're much better off not slicking a system and signing up for VirginMobile (I was lucky enough to get the $25 plan, now replaced with $35) that gives unlimited data and 300 minutes. Unlimited both is $55.
Or maybe you'd consider Republic Wireless' plan with "550 minutes, send 150 texts, and ... 300 megabytes" for $19 a month after a phone for $180 -- both are without contracts.
There are "deals" for those who want to find them for both (though how folks get by with so little data, I have no idea).
The question really is how much it's worth to own an iPhone over an Android. Is it really $300+? Luckily for Apple, many think so. I love iOS on my touch; I'm just too cheap to shell out for the iPhone.