ps2 disc read errors?

I need some solutions to fix scratched ps2 disc's or it may be due to m ps2 partly along with scratches. DETAILS- I just bought a ps2 because i have several of games for it that i wanted to play after my previous one broke. The one i bought is another slim and it was used but in pretty good condishion. I know that the ps2 especially the slims are prone to reading errors due to cheap lasers but i'm not sure if it's the games or the ps2. I can play other games which are sort of scratched and after a quick swipe down they work perfectly. The problem is with my gta san andreas disc's/gta vice city; i have two copies of SA which are both scratched badly but they start up perfectly and after a few minutes of play they give the famous disc read error. I the tried toothpaste trick along with cleaning and chapstick tricks with no results accept they got worse lol. I cleaned the ps2 after a few disc read errors and after that the 2nd SA disc worked for awhile then started acting up out of nowhere. SA is the main reason i bought the ps2 and i've been dying to play the game. I live about 50 minutes away from any places that have disc buffers so avoid that answer unless that's the only thing i should do; also if you might have some info on how much gta SA might cost at a store that would be nice. Thank you, 10 points to any answer that helps me or fix's my game