Daryl, if the color doesn't matter to you, hit a professional painting or auto body painter and see if they have waste powder available.
Another guy on the other site did that and came away with 60lbs of mixed color overspray that was a dark brown gray
Apparently, the sprayed powder that doesn't adhere to the part being painted just falls to the floor and is swept up for the waste bin.
Or, buy it at Harbor Freight of they are in your neck of the woods.