I was in a very similar situation a few weeks back. I painted a temporary screen using Sherwin-Williams ProClassic Smooth Enamel Satin Extra White, # B20 W 51. It was about $25 for a quart which painted my 120" screen with two coats. I primed the area with two coats of primer first and am very happy with the results. I think with the rollers, paint and primer, I walked out the door for about $45. This is my first projector and so I can't compare to anything, so YMMV.