Try Catalina Direct
I got a new mainsail cover from Catalina Direct. It has a Catalina logo on it and I am very pleased with it. Catalina Direct may not be the least expensive, but their sail covers are specific to C-22's and fit perfectly. Their covers are for sails with sail slugs and a sail stop holding up the downed sail just abouve the sail slot opening. I think the price is around $150 to $160 before shipping. But no sales tax since you do not live in California.
