How can I store large beauty dishes without buying expensive cases?

A low-cost alternative people have used for smaller beauty dishes is a cake caddy, though that tends to work only for dishes around 12 inches or less. For beauty dishes in the 20–22.5 inch range, the same idea may be hard to find in a large enough size, so there doesn’t appear to be a widely accepted cheap off-the-shelf solution from the answers here. If you’re thinking along similar lines, a rigid round container is the right general approach, but availability in the needed size is the challenge.