Yeah, I went the "imitation" bulb route a few years back with my previous projector, and not only was it not as bright, but colors were off, and overall projector image was more "dull" and faded looking. Dealt with it for about 6 months before biting the bullet and getting an OEM bulb. Night and day difference, it was like having a new projector again. SO much better.
But like Matt says, you could try it, and if nothing else sell the projector with a working bulb. Of course if I was the buyer of the projector, I would hope for a certain level of performance, and if the bulb was not able to produce a decent image, I would feel a bit shafted by the purchase.
