At the Winter Social earlier this year I won a flytepacker raft. It weighs just under 2.5 lbs and retails for about $300. Less expensive than the Alpacka rafts, but not as durable either. However, for floating around a lake its plenty durable enough. I’ve bumped into the occasional sunken tree branch or other debris with no damage. I’ve used it about 6 times so far and am very happy with it.
http://flyweightdesigns.com/FlytePacker.aspx
Jacob