What are some methods of fixing scrathed game disc?

Also, do stores (gamestop, blockbuster) also repair disc and how much? Thank you.

Some Gamestops have this liquid stuff that works really good.

Why don't you get a game doctor?

Game doctors are kind of janky, I'd check your local Blockbuster and see if they have a disc resurfacer, which is somewhat better than the Game Doctor.

You can also use a dremel with a buffing wheel and a steady hand.

Use toothpaste. YouTube it, it totally works