[hl2k3]

Well this is all dependant

If you want Supra Style headlights your going to have to cut into the body and fit them, doing it yourself is a helluva lot cheaper than having someone do it, BUT your looking at the quality of the job in the long term.

If you want the flip lights like the 5th gen had, then you're looking at a different kind of install, you need to mount them and leave room for the motor, you need to run a new power connection, fuse, etc.

Or just buy a supra/5th gen :P