Try install some homebrew.. If it doesn't load (and gives a black screen, not just an error code) then it's the logic board.
If homebrew works it's just the laser or tray, but you could just use games that work discless (GT5, Just Cause 2, MW2, SBX etc) and not have to spend a penny if it's only the laser.
Ideally you should test to see what's wrong (mainly if your logic board is okay) and then buy a working drive with a laser included.
I tend to get them from YLOD machines since you get a discless machine for a little more than a refurbished lens on Ebay that way (if you can fix YLOD), but more importantly an original lens (most of the time). You can find one locally, I get them for as low as €30 depending on what's wrong with it.
TL;DR Buy a YLOD with a good BR drive that matches, once it's not your logic board that's faulty.
oralphie: Will this allow chuck norris to play backups??? PLZ HELP!!!