Whether people are interested in the product at first will depend on kayak design, not the plastic. If it's a good design, people will buy it. If the kayaks hold up and do not break when being pushed to the limit, people will continue to buy them. If the boats start breaking, you will not have a customer base for very long. As far as plastic goes, people tend to prefer the cross-link (Jackson) to the Linear (most other companies) because of its structural integrity. That being said, Dagger, Prijon, Pyranha, and LiquidLogic have reputations of making boats that hold up well too.
Most often, people buy boats from retailers because they have the ability to demo the boats and size it up in person.
"The world would be a better place if everyone kayaked."-Brad Ludden (Valhalla)
"You only get one chance to run a drop blind."-DD