iMac SuperDrive Acting up

I have a 20" Intel iMac. The superdrive will accept and read DVDs fine (both DVD movies/games and blank DVDs) but will not read any kind of CD. When I put in a CD I can hear the drive trying to read it but it just spits it back out after about 10 seconds. Is my drive going bad? If so, I'm out of warranty so I've heard from others that it could cost upwards of $400 if I go to the Apple store to get it replaced! Could I just buy an external drive via USB or Firewire instead?

Any advice would be greatly appreciated!

Generally when a drive starts to act up it's the DVD read\write which seems to go out first. The optical light source requires more power to act on a DVD than a CD. So I would suggest you first try cleaning the drive. A cleaning kit can be purchased at most stores which sell computer accessories.

If that doesn't work, a USB external drive can be purchased for less than $100 and should work well enough for reading\writing and even booting the machine.

Regards.