I believe that you are stuck having them custom made. I could be all wet behind the ears in making that statement but I don't think so. Just start making some calls to shops and start getting prices. At least that way they will be right and should be backed with some type of warranty.
Of course they will want the boat itself to measure - keep the travel time in mind.
Any good sail shop should be able to make one for you. there is a good one on I94 in racine county wi. I forget the name but if you need it i could drive by.
Yep -- custom made is the way I have had to go in years past. I paid $700 for both cockpit and bow covers custom made out of Sunbrella from a small independent guy. I had quotes as high as $2000 from big city shops for the same thing. This time I got the cockpit cover made long enough to cover the windshield -- good for protecting the instruments and front seats against UV deterioration.