I cracked the screen on my iPhone 4?

Found some places that'll do it for around 90$ 2 of the places are in the mall. I'm worried it will mess my phone up somehow and I don't want that to happen. Feedback please? /

You can get a new one from the Apple Store at half the current price of an iPhone 4 with your carrier. I'm not sure if you have a no-contract then I can't help you.