The two most popular low cost ones right now are the infocus X1 and the BenQ 6100. Do some reading on AVS Forum. The BenQ is supposed to have the edge for all-out projection quality - but the X1 has a better built-in deinterlacer. The benQ is also supposed to be a touch brighter.
On a related note, I bought a BenQ 6100 (I've put about 6 hours on it) and I'm seriously considering selling it. Movies look fantastic - but my room shape and layout doesn't lend itself to the projector experience.
If you're interested, shoot me a PM - I'll decide whether I'm keeping it or not in the next week or so. The unit had a $100 rebate, so I'll be selling it at the post-rebate price, without you having to wait 2 months or whatever, and I'll eat the risk of not getting it. I'd even throw in the ceiling mount I pieced together at home depot, and a component-to-vga cable I spliced together.