Clint,
I purchased the kind of cover you are looking for from the Hobie catalog/dealer. I believe it was around $180 U.S and I am very happy with it. I understand from talking with you in the past that Hobie stuff can be a lot more expensive down there. But, if you can get that price (or close to it) I think it might be worth it for you when you factor in materials - plus all the work you will have to do on a nice cover. The Hobie cover comes with bungees, tie-downs, velcro strips and instructions showing how to easily modify it for shrouds that are left in place.
Dave