Try some of the internet/mailorder sources as well. You can get Dacron for less(depending on the thickness) than the duck you are looking at, from Stimson or monfort or Dyson. The duck must be stretched into place where the dacron is heat shrunk. Also, the cotton must be replaced every few years; the Dacron os a lifetime skin, if protected from UV.

There was a guy on the east coast who covered his kayaks with the coated fabrics from the awing shops, but i don't know how he fit it. I have heard here of people cutting this stuff into panels matching the space between stringers and gluing or welding the seams.

The baidarka archives are full advice on skins and coatings.