Cracked iPhone 4S glass front and back. Where do I get parts?

I've got a cracked front and rear glass casing for my iPhone 4S. My friend had hers replaced a while back and a subsequent insurance claim was rejected on the grounds that her front screen was not an official apple product.

So I guess I'm asking for a supplier of official apple spare parts OR how much would it cost me to get this repaired by apple?

EBAY