Roughly $30 startup, $104.99 a month. You're required to purchase the unlimited data plan, and that's where most of the money goes.
Edit: Also, it's a minimum TWO-YEAR plan, with major fines for early cancellation. Bear in mind, Verizon's getting the iPhone later this year. Maybe you should convince your family to delay your present. AT&T is terrible, and Verizon's coverage is amazing.