Graham -
Just a bit of unsolicited friendly advice if I may!
Being new to the laser projector scene myself, I certainly understand the enthusiasm and desire to get "lasing" as soon as possible! However, as others have aluded to, constructing your own laser projector is going to involve a LOT of small wiring projects that require a basic knowledge of some electronics, power supplies, soldering skills, etc. You certainly don't need to be an expert in all these areas (I'm living proof of that!), but you are approaching a point in your project where not really knowing what you're doing could possibly lead to a very expensive mistake!
Perhaps before you go any further you might want to consider spending a few dollars on some sort of electronics hobbyist kit and / or books, and get a little bit of practical hands-on experience with something that doesn't cost quite so much if the (+) and (-) wires are crossed when you apply power!
This is by no means meant to be bashing - just friendly advice from someone who has been there and done that!
RR
Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
1979.
Sweet.....