How much would 3 iphone 4s s a month be?

My mom and step dad both have iPhone's on at&t and i really want an iPhone. My plans up next month and i want to know how much adding another iPhone would be.since we wold have 3 iPhone's it would be cheaper for each, every month right? (all iPhone 4s)

You will have to ask a ATT employee. They are the only ones who can give you accurate info about plans involving minutes/data/messaging. Plans, phones, and prices are constantly changing.

Straight Talk prepaid: unlimited talk and text with 2 GB of data, $45 a month per phone. I'm positive that even an identical AT&T family plan makes each phone's service cost more than $45 a month (more like $70-80). Don't get turned away by the fact that you'd have to purchase an unactivated phone if you chose prepaid. The phone is expensive both through AT&T and unactivated because they don't tell you that you pay about the same for the phone in the contract as you would unactivated. For example, if you paid $199.99 for the phone up front, the service might cost $90 a month. But if you bought the phone unactivated ($500 new) or used one you already had, the exact same service would cost less, say $80 a month because the continuing cost of the phone isn't included.