I made this a couple years ago, but I'm just now getting this on Instructables to puff my profile just a little. I built it according to this well done (if long) tutorial: http://www.instructables.com/id/Build-a-Greenland-Kayak/
This is not something you can just slap together, but that being said I'm surprised how doable this project was. I wasn't keeping close track, but I think this cost about $500 to make. It came out at about 13 feet (the original tutorial called for a design 4 feet longer, but that was the most I could legally transport in my car), and weighs in around 40lbs. The sides and keel are made from Douglas fir, the bow, stern, and beams are made from hardware store pine, and the ribs are made of hardware store oak. Everything is fastened together with a combination of nylon twine and 1/4in dowels.
Looking back, that initial shaping of the sides was freaky. I'd never bent wood like that before and just expected the whole thing to explode at any moment. It was surprisingly easy to bend the ribs; I'd never done it until I made this, and you might be surprised to hear that it can be done in your kitchen. The skin is made from ordinary cotton canvas (bought at half-price to avoid paying $10 per yard!), painted in latex house paint from the hardware store.