Stop guessing, and stop looking at projectors, and please start doing some reading.
The Optoma HD66 is about the cheapest model I can imagine using or recommending to anyone. It will produce a decent image on a 100"+ screen and can be had around $500.
It is well reviewed and has a strong history.
It is also several years old.
I would recommend that you up your price point a bit and go with the BenQ W1070 or similar. For $900 you can get full 1080p for HDTV viewing and with plenty of brightness and a shorter/medium throw lens which can get large from a 12' throw distance.
From 12' the HD66 can hit a 106" diagonal.
From the same 12' the BenQ W1070 can hit a 110" to 143" diagonal. So, you can get a fair bit more size from it.
Up to you really... But, avoid the LED models, they aren't appropriate for any serious use whatsoever.