Projectors themselves are frankly not that expensive, but as you say, the bulbs is what costs. I've no idea how much you use your projector, but be sure to buy a projector with bulbs of 3000 hours of runtime at least. On the projector here we have yet to change bulb in about 4 years, though I watch films and play games on it.
If you want to invest in a new 1080p HD projector I'd do that as you can get bulbs lasting a really long time on them. I'm not very updated in that scene at the moment however
If you want to be able to view in a semi-light enviroment, get a (I've no idea what the word in English is, so bear with me) 'white blackboard-thingy that is made of some canvaslike material' to project the picture on. In the upstairs livingroom the even wall is simply painted white, so we project directly on the wall. But a canvaslike thingy will reflect the colours better, making it better in a not all dark room.
You should perhaps tell us something about your budget, roomsize, if you want HD or not and what you mean about not so dark room if you want a satisfactory answer
