Using a projector is a great way to get that real home theater feeling. And with the improvement in quality of these beamers you can get a high definition image in a screen size that you'll never reach with an LCD of plasma television. The only thing is you do need an empty wall that's large enough. And projector screens are very ugly or very expensive if you want to be able to roll them up with the touch on a remote (and do you really need another remote?).
This is where
Screen Goo might come in handy. It's basically a paint that is made to reflect light, much more than a normal white paint. This will give you much brighter colors from your projector, just like a projector screen would do. According to
this DIY guide you'll first have to make the wall totally smooth and even. So it might be quite a project.
Prices for a bucket of this magical paint depend on quantity and color.