I think the H180X will be the 'cheap' projector to get for people.
At a similar $500 price point it offers one of the most comprehensive packages around.
The W770ST is certainly a worthwhile competitor out there:
On paper, the Optoma has slightly better contrast and is slightly quieter, but both are similar models overall and I would expect similar performance.
The biggest difference is the throw distance, and it is just reality that longer throw projectors produce a bit better of an image. If you aren't using a fixed frame screen and have any potential to bowing or waves in the screen, the longer throw of the Optoma will be a very important feature.
But, both should be expected to produce very good images on screen for a great price. The big limitation with both is the 1280x720 resolution, which begs the question of whether or not you can't muster up $300 more for a 1920x1080 projector.