You aren't being realistic.
Projectors are designed to deliver video to average size screens. In the business world, this is a fairly lousy image up to about a 10' diagonal for under $2K. For home theater, it tends to be a somewhat darker image, but higher quality video, for under $2K and about the same video size.
If you get out of these specifications, then costs go up significantly.
If you are in a completely dark room (100% dark) then you may be able to go with a double stack of the AX100U projector from Panasonic and get about a 20' diagonal for about $3,500 and with that, I would still use a decent 1.4 or so gain screen.
That's probably what I would recommend.
A better bet would likely be something like the Sanyo PLV-WF10 projector. Which is getting further from your price point.
Keep in mind, a 60" plasma still tends to run well above your budget for quality units, so what you are talking about is about 5 TIMES that size in diagonal and about 25 times the surface area! For the same price, it becomes more clear that it isn't realistic - even in perfectly dark conditions.
If your situation isn't completely dark, but may have some typical indoor lighting, then you will need a projector that delivers, real world, over 12,000 lumens. I would recommend closer to 20K lumens.