I swear by these. It's the Tuchtech folding kayak. ~30 pounds 350lbs capacity, folds up and is easily carried on your back. $350 and 2 year warranty, but they'll still replace it after that as long as it isn't user error. I've had mine for 3 years and love this thing, as good or better than any standard kayak. The owner is also a pretty cool guy, I had a seem pop after a year. When I emailed about getting a replacement the owner called me himself and was really cool about it, and sent me a new one in a week. He also went into how they make them, and knew exactly what went wrong and explained how they've improved their techniques.
Only down side was the tracking fin being flimsy, but I've never had trouble tracking. They've also updated the fin since I bought mine, and looks a lot sturdier.Tucktech.com
, just watch the video.