The Sevylor Trail boat is not shown on the Sevylor website as far as I can tell, and a web search for it came up with lots of out of stocks and a few discontinueds, so I think it is gone. I haev one, which I have only used a few times, and it is fun to paddle around a lake in. I'd be leery of any moving water, as the thing is pretty hard to control.
A lot more expensive, but looks like a lot more boat for even less weight:

http://flyweightdesigns.com/default.aspx