How much is a iphone 5 plan a month.i want the cheapest plan with internet possibly?

I want a iPhone 4 or 5. How much would I end up paying I'm only 15 and I'm a girl so how much would it be a month after you buy the phone for 200 dollars or so I think

On Virgin Mobile USA, you pay $349 for the iPhone 4 or $449 for the iPhone 4S BUT YOU ONLY PAY $30 DOLLARS A MONTH!

Yes, you heard me right! $30 a month for an iPhone. $30/month includes 300 minutes, unlimited texting, and unlimited internet.

I have Virgin Mobile USA and I like them a lot.