Does game exchange do disc buffing, has a xbox 360 game with some scratches on it?

Yes, however they will not buff Blu-Ray discs because of the risk of removing a layer of data near the bottom of the disc. Xbox 360 games are fine. No Blu-ray movies, PS3 games, or PS4 games. Everything else is a-go. I'm not sure about price. At one point it was $1.25 but now i believe it is free. I am not 100% sure

Yes, they do. I think it's free.