I doubt sincerely that you can get even part of your list for under $500. We've paid more than that for some individual painted canvas backgrounds, and close to that for some of the best muslins. Background stands and mounts can exceed that budget, too. While we have a permanently installed motorized background system in our studio as well as another that is chain driven (both for painted canvases), we also use either of our two portable background racks for muslins. One has "jack-up" legs at either end for wedging between the floor and ceiling, and the other is more portable and reminiscent of light stands with a long pole suspended between them. With either of these two, the stiffness of the horizontal mounting pole is important. The latter gets the most use for our location shooting, because we can use it in offices and other places with suspended rather than rigid ceilings, which are very common in commercial buildings. It also breaks down into a very convenient canvas carry case.
We got all that hardware from Calumet, except for the motorized unit, which we got from Denny. We have backgrounds from both sources, as well as some custom canvases from smaller companies.
If you're really on such a tight budget, you might consider what we do when travelling. We go to Walmart or whatever large drygoods store is nearby and buy king sized velour blankets for backdrops. They're available cheaply in a wide range of colors. We still use the portable backdrop support I described last, to which we affix the blanket (or muzlins) with the large "clothes pin" style clamps available in most hardware stores. You could do much the same in a home studio or on location.
As for colors of backgrounds, we select those based upon the skin tones and wardrobe of the subjects, as well as the direction of the client on commercial shoots. At last count we have over a dozen canvases, 20+ muslins, and who knows how many blankets. Black and white are good places to start, but I'd add gray to the list of most useful along with medium- to pale blue. And for size, we use 10'x20' (roughly 3x6 meters) muslins for large groups when hung horizontally or for uniform background and floor when hung vertically and draped out onto the floor toward the camera. Smaller sizes are okay for general subjects provided they will reach from the ceiling to the floor at a minimum and are about 25% wider than your widest subject groupings. Dimnesions are listed with each backdrop at both the Denny and Calumet sites.
As for gels, we rely mostly on primary colors, neutral density and occasionally polarized gels. We get them from Calumet also. We use them a lot on backgrounds, but also for creative effects on some subjects.
