Your post reads like you're inclined toward a DIY route rather than a manufactured, or DIY frame with some form of commercial screen fabric. You may want to go that route if only to give you some time to finalize aspect ratio, size with respect to screen wall, room, view distance, screen gain, etc. Suggest you post a similar question, if you haven't already, in the DIY screen subforum. An inexpensive start though would be to purchase several yards of white polyester from a fabric shop (Hancock, JoAnn, Hobby Lobby), cut or fold to a starting size and affix it to the screen wall. Then go from there - lots of good info in the DIY section. If you rule out DIY, at least you'll have a better handle on what to look for in a commercial screen.