Well a new Main cover at WM was close to $375, and mine was beat to hell and attached by bungee cord at this point, so I opened up Don Casey's excellent book and got to work:
After spending under $50 on two yards of Sunbrella fabric, I had the thread already, $8 on a YKK zipper, $5 on binding tape and $20 on the twist button attachments (no need for a punch, heated up knife works fine- thanks again don casey) I have a new mainsail cover:
The main is shorter than the boom anyway so why pay for an extra yard of fabric?
$83 and it took about 10 hours total, using the old one as a template. Much, much easier than I thought it would be to tell the truth.
It was so easy, in fact, that for my next project I am going to follow Mr. Casey's directions and use the excess materials to make a mainsheet bag for the cockpit.