Recently I decided to stop repairing and finally replace my old mainsail cover. I found a couple of sources, but they wanted more than I wanted to pay for some pretty generic looking covers. Then I found
leesailcovers.com/ which seems to be run by a Becky Randolph.
She sews custom covers to order. She was very helpful online and she has an I.M. gadget on her website for direct conversations when she's in her sewing room. I was able to get a new cover for my Ranger 26 for about $143, custom made. It fits great and seems to be the best quality sail cover I've ever seen.
I am so impressed that I'm trying to pass the word.