My son broke his AT&T iPhone?

My son is 12 and he dropped his AT&T iPhone 5 while he was playing basketball with friends today, and now the screen's cracked. The phone is over a year old so what's the cheapest way to get it repaired or replaced, with out DIY?

I don't know how to get it fixed, but if you do get it fixed (or even do it now to prevent more damage) get a good, hard - wearing case:
http://www.amazon.co.uk/...B0099VXLCU
I have this for my iPod 4 and it refuses to break of have any damage whatever I do to it

If you find repairing it is too expensive I would suggest selling it.
There's a great website that buys old and broken electronics. And the offer best prices on the market.
Check it out - http://sellbrokenelectronics.wordpress.com