How much would I pay for an iPhone 4 monthly?

We have a family plan with 4 people right now. I wouldn't need unlimited texting because of iMessage, and maybe 30 hours of calling each month? Maybe 40? I don't know I usually text. And I would want internet!

What carrier?

Minimum rate would be around $70 a month for the three carriers (AT&T, Verizon, Sprint)