AVR2 is correct, they are way out of date. I bought a barely used one last year, which is okay, but I must say it is looking a bit antique these days sat on top of my ACD.
Unless you can buy one that has never been used, I would not expect much life span from a second hand one since it is a few years now since Apple stopped making them.
They were great in their day, but other manufacturers have now made better compatible and quality models, for Mac users who don't have a screen with a cam already installed.
If you really want one, you pick one up off ebay.