You are really below the bottom of the line junk out there with that budget.
When 'average entry level' for this stuff is closer to $500 or so... for ENTRY level, then your budget leaves you in a poor situation.
You will have to scour some of the websites for cheap/refurbished projectors on sale. You can't afford a used projector, because that will come with headaches you can't afford. You also want to check for the best warranty possible so you aren't in trouble when it breaks.
Things you REALLY want:
At least XGA resolution (1024x768 native) preferably wide screen (1280x800 or similar)
HDMI or some other digital input - On the cheap projectors this is still NOT standard!
As many lumens as possible - contrast ratio is irrelevant at this price point
About the best I could find is this:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=8524160&Sku=QTM-101772781
At about $100 more than you want to spend, but certainly is about the most acceptable thing that I would recommend.
HDMI input, 2,200 lumens, 1280x800 aspect ratio
You might be tempted by something like this:
http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=8744871&Sku=QTM-102180433
But, that's up to you. It does NOT have any digital inputs (HDMI), so you must feed it via VGA with your PC.
Keep in mind, replacement projector lamps are about $200-$300.