A couple of months ago I had a cover made for Coot by the very nice people at Trident,
They do a made to measure service which I think is very reasonably priced, and I was really pleased with the result.
Then, being a real cheapskate, I wrote a review of the product and sent it in to Water Craft Magazine which you can read in the latest edition.
Available from only the finest newsagents. Its probably best to get a subscription.