Rugs are good.
But if you want the cheapskate option, go to a large shop that sells carpets (local choice Boyes). They get carpet delivered wrapped in very thick poly sheeting, and have to get rid of the stuff after they unwrap the new stock delivery.
Have a friendly word with the staff, explain that you want some for painting dustsheets, they may let you have one for free. Trim to size with scissors, bin after use.
We use a few for school work - they make good table protectors and can be trimmed to size (and are free).