Find out what the problems are first...
If it doesn't read discs (the clock in the right hand corner will usually just constantly spin in this case), then you're ok. A laser is cheap to buy and easy to replace. If it's any other problem, then it might be a broken logic board.
Stay away from PS3's with broken logic boards! They're a nightmare to fix!
I suggest that, if you do get one with a broken drive, at least try to fix it. Otherwise people will assume you're downloading games when talking about PS3 titles and be very reluctant to help you should you have problems. I also find games work better if you leave a disc in the BD-Drive (I keep all my PS3 games on the HDD and leave one of my originals in the drive so I don't have to change discs when I want to change games).
60GB (120GB WD Scorpio Drive) PS3 (CECHA01, NTSC), 3.7OFW
60GB (640GB Samsung Drive) PS3 (CECHC04, PAL), Kmeaw 3.55, Repaired (Dead Laser)
PSP-1003 FAT, CFW5.00 M33-6 & Prometheus v2
X-Box 360 Xenon (JTAG'ed, 500GB HDD)