Consumer reports recently (4th qtr 2008) listed some HD projectors as their best buy - most were under $3,000.

I would definitely go that route (if I had somewhere big enough to project an image that big), and have seen some pimped out systems where the projector retracts into the ceiling when not in use (as does the screen)

I can only imagine a 5-person shooter game on a 5' x 10' screen