I have used Moose River Handcrafts, http:/home.earthlink.net/~mooseriverhandcrafts
Good service & good knife. Or, P. O. Box 205, Jackman, Maine 04945.
Also, I saw that Scott Barkdoll, Skywoods Canoe had some at the Assembly this summer. www.skywoodscanoes.com
Both of these companies advertise in WCHA's magazine, "Wooden Canoe" please support our generous advertisers.
If you want to make your own try a "google" search, I have seen the articles but cannot remember right now (a senior moment!) or you can get the blades already made up from Lee Valley Tools...just add the handle per the enclosed instructions.