I've made a kayak using PVC coated polyester fabric used in the tent and awning trade. Cost was $80 Can. The material has very little stretch thus is difficult to do around compound curves. My hull was a Greenland type with hard chines and was done in four seperate panels for the hull and two for the deck. Worked out great. The seams were the more difficult part. Heat welding as mentioned in other responses made ugly joints as the fabric core always telegraphed through. I used a solvent weld type glue and with some experimentation came up with a joint that could not be broken without tearing the PVC coating right off the fabric core. The material is very tough, nearly impossible to puncture with a screw driver and it takes a very strong person to tear it even after an edge cut has been made to start a tear. The product has a local (Western Canada) trade name of "Faltec".
: I saw a while back about someone using hypalon for a frame on skin yak. The
: idea intrigued me so I did a little investigating, the only source I've
: come up with is shipstore.com who estimated I would spend abou $6,000 for
: the fabric (ouch). Maybe not such a good idea after all. I'd still like to
: do some kind of plastic skin on frame, anybody have any ideas where to get
: cost effective (cheap) material and what I should look for?

: Thanks