How much does it cost to repair the back panel of an iPhone?

The back of my iPhone 4s is cracked. 2/3 of it is all cracked, but the phone works fine and so do the speakers and mic. The only issue are the cracks. My warranty is up.

I'm 13 and I have to pay for it. Please help?

You would need to take it to apple store some best buys are an apple store if they can't fix it which I'm sure they can tape it up with clear packaging tape. Good luck Past hey would keep your phone so they can send it out is it still under warranty did you buy insurance on the phone when you bought it