There's actually quite a lot of information on the web; in addition to the Paleoweb site indicated there are commercial makers, enthusiasts, and university anthropology-types.
If you get the Military Channel, the show Weapon Masters had a segment on the weapon, and there are some short videos up on the website. Go to Military Channel and do a search for Weapon Masters.
I built one a few years ago, pretty crude but quite functional. I just roughed the shape out of a piece of lumber and filed/rasped it into shape.
Used a very traditional

vinyl-covered aluminum garden stake as the dart, complete with duct-tape fletching.
Silly thing flew quite well with a bit of added weight up front.
Since then, I've gotten a large number of wild turkey feathers I use for fletching arrows, and I plan to use either bamboo or river cane shafts to make a more traditional dart.