I use an APC Smart UPS series on both my computer and projector.
The smart ups series has the true sine waves instead of the simulated sine waves. I don't think simulated sine waves are hard on your electronics, only on electrical motors from what I understand. I believe a projector should be safe with a simulated sine wave. You can get retired Smart-UPS series units off ebay for next to nothing. I think I paid about $120 for mine off the normal 3 year lease from an ebay seller --- battery purchase will often be soon expected on a used unit, but then again I paid $100 and not $2000. If you find them local and go pick them up then you can save on the shipping...
I ran a long power cord to the UPS which sits on the ground. My UPS is also hooked up to my sump pump in the basement. it's a 2,200 va model.

I won't be putting it on the ceiling because it weighs about 120lbs.