I've been considering building a LCD projector, and I just recently stumbled upon this site. Before starting, I have a few questions.

Can you use LEDs instead of a lamp to light the screen? It seems like it would be cheaper, it would last longer, and there wouldn't be a heat problem.

No one has been able to get the brightness needed through LEDs. There are A TON of threads talking about this issue, so look around a little and you'll find MUCH more about it..

I think I'm going to go with a lamp.

Does any 400w electronic ballast work, and are there any online stores that sell used LCD monitors preferably ones with broken backlights(cheaper)? I could just go the EBay route, but I'd rather buy something from an actual store that I can contact if anything is wrong with the screen.