Re: Poor college student needs 720P Projector
You could probably find a good deal on a Mitsubishi HC1500 -- those aren't TOO far above your price range when purchased new. Not sure how big the used market on those is yet, since they've only been out about a year (if I remember correctly). That projector's predecessor, the HD1000u is very similar in performance -- and since it's slightly older, it may be easier to find used (and could probably be had cheaper).
If luck smiles on you, you might even come across a Mitsubishi HC3000 in your price range. This projector is in the same family as the 1000u/1500, but its color wheel doesn't have a clear segment -- as a result, its peak brightness isn't as high, but it can achieve darker blacks (so it'd be a good fit for a very dark home theater room).