I got screen material off eBay and built my own screen. Just wood, fabric to wrap the frame, staples and screws. $80 for the screen material I think I paid, it's not as good as some of the really expensive screens, but good enough for what I want.
There's also paints you can buy, paint the screen right on the wall.
Costco has some as well:
http://www.costco.ca/Common/Category...n-CA&whse=BCCA
EDIT: Projector I ordered online.