The screen is as important as the projector - the color and 'reflectivity' of the screen will impact the quality of the image as much if not more than the projector. There are several screen types and you can make your own (paint of some kind, lots of formulas are on available on the 'net, on the wall or board or over 'canvas' on a stretcher frame idea).
If you are in a pretty dark room you don't need a lot of power. The more ambient light, the more power you need for a bright, contrasty image.
I just got a lower end epson on sale ($400 on a black friday deal) and have been satisfied with it. My average sale TRIPLED as soon as I started using it over printed proofs. I mounted mine to the ceiling using an old tripod head and quick release - easy to level and take down if you want to take it to your living room to watch a movie
I've also used mine to project my logo onto walls and a signboard to make my own signage. Must be done at night though.