I cracked my iPhone screen

Today at work I dropped my iphone (4) & it landed facedown & cracked. Two of the corners are cracked there's a few cracks in the middle. How much would it cost to get my iPhone screen fixed? & what are some places I can get it fixed at? Also, do they charge on how badly cracked your screen is?

Toothpaste

You can get a replacement from eBay but the screen won't be as good as it was before. It will cost around 26-30$ and shipping.
Hope this helped.