iMac no longer reading/playing CDs

The drives in iMacs, Macbooks and most laptops from other manufacturers are designed for small size, not durability. It can be replaced but as Tan43 suggests, a better, cheaper alternative is to get an external drive, especially with an iMac where portability isn't an issue.

Puerto - that does seem like a reasonable price for replacing a disc drive and the
replacement of it shouldn't put your music library at risk since those files are on
your hard drive.

And you have your music library and all your other files backed up in at least two
other places as well, right, just in case?