Currently, I have a family plan of 850 minutes for two lines with unlimited texting on one line. I pay around $100 for this plan. When these lines are eligible for an upgrade, I would like to switch to the iphone, but am unsure how much more it would cost for the unlimited data plan. Would it be cheaper to upgrade both lines on the family plan to the iphone with the unlimited data plan for both? How much more should I expect to pay for the iphone package?