If the problem's because of the discs being scratched, then that one's solvable

You just need to figure out which discs have got problems from the scratches. Then, ask your local game shops and find out which ones offer a CD resurfacing service. Find out which one's the cheapest, then go for it!

Resurfacing is reliable as long as the scratch isn't on the label-side of the disc. As long as the scratches are on the surface (the black side for PSX discs, silver on normal CDs), then that surface can be removed and then replaced with a new one. My second-hand copy of Syphon Filter was badly scratched and used to crash or skip a lot, but then it got resurfaced and now it's perfect. When I bought Metal Gear Solid 2: Substance, one of the DVDs had white stuff on it. Resurfacing fixed that too.

Don't worry, there's no need to shell out your hard-earned money for a replacement, hopefully!