Obviously, to build a projector you will need a set of scanners.
You will also need 3 lasers (red, green, and blue), along with a set of dichros to combine the beams and some mounts to hold and adjust the dichros.
As for the dichros and mounts,
Laser-Wave has some *very* competitive prices on both. I think
Stanwax (another member here) is selling Laser-Wave products now. He's located in the UK, so he can ship to you fairly easily. Also, the head sales representative / technicain for Laser-Wave (
Bridge) is also a member here on PhotonLexicon, so he can answer any questions you may have about his products.
Have a look in the gallery and you'll find lots of pictures of people's projectors. (Each "album" opens up to reveal lots more pictures, and sometimes extra albums as well!) Some of our members have detailed photo records of the entire process of building their projectors. These pictures are a great way to get an overall plan in your head before you try to sketch out your own projector design.
Also,
there is a wealth of information in the posts here. I know it's a lot of material to go through, but a weekend or two spend reading the older posts can *really* help you get up to speed on how to go about building a projector.