What is a good cheap place to go to get an iphone 4s screen repaired?

I live in Charlotte NC, and my dad recently dropped and broke the screen on his iphone 4s, he doesn't want to by a new phone because they are expensive, and apple charges like $80 for a repair, at that point, a new phone is better, (android of course, he likes android more than iphone now that he tried iphone)
my teacher told me of a place that did screen replacements or molding or something for $20 but i can't remember the place, is there a place like that, that is kinda cheap, i don't think my dad will pay more than $50 for the replacement

Ask the teacher.