Where can i get a new iphone 4 front screen?

I cracked my iphone 4 front screen and am looking for a good reliable replacment kit to buy and don't know where to buy them offline from, and the ones i see have a weird chip coming out of the top in the pics, help!

Anywhere really, they sell them on ebay for less than £10! But if you want to be safe, try Amazon - they sell everything!

Amazon.
My friends replacing hers with a screen she bought off of there!