What is the average Iphone Bill with AT&T? (2012)?

My thing with thinking about iphone users is that their bill is over $100 and i'm not interested in paying that much money for a phone monthly. I would consider it, but the bill has to be reasonable…

Your concern is absolutely valid.
Ignoring the contract and initial cost to purchase the iPhone, I'd say the *AVERAGE* monthly cost is about $100.
Keep in mind there are so many variables, and bills can be lower than this, and they can be higher. Additional features (e.g.additional fees) include upgrading to more than 200 text messages per month for $15.

It's about $90. I'm with AT&T and here is what I pay:
$39.99 450 minutes with rollover, 5000 night and weekend and free mobile to ANY mobile(lowest plan)
3GB data $30 (the lowest is $20 but its only for 300MB)
$20 unlimited messages
The taxes on my account come up to about $8.50