Sometimes during sales or specials, you can find an Optoma hd20, Acer 6510bd, or a Viewsonic Pro8200 (usually only refurbs) around that price.
There is a place in this forum (dedicated thread area), where people discuss the latest deals and prices.
You want at least 720p Native, but all three of those projectors above are 1080p which is higher than 720p. You don't want anything less than 720p, and if you use a lower resolution PJ sending a higher res signal, it is re-scaled (you had the right idea, but cropped is not the word I would use).
Hope this helps...