How much is the iphone 5 on t mobile with the family plan?

I might get the iphone 5 for my birthday in a month and my mom says if the iphone is full priced (700 dollars) i can't get it, so how much is it with the family plan on tmobile?

Added (1). And how much is the 16gb or 32 gb?

Ya you know this and all price list are here check http://theworldofcellphone.blogspot.in/

SInce you are on a Family Plan, the iPhone 5 will cost $580. 99 down payment and you must pay it off all at once.