Duckworks is a great source mentioned. In Central Tx you'll get the stuff almost the next day.
I would also suggest to you a trip down to Port Aransas and Farley Boat Works. They have quite a few pirogues they have built and restored over the years and you can see some first hand. Its a shop for owner/builders, mostly 1st timers so they would have a lot of suggestions for you, sources etc. Frank and Rick will be happy to help you out I am sure. You can find em on Facebook too if you want to check them out.
Alamo Hardwoods in San Antonio is a good source for marine grade lumber but I second or third the opinion you really don't need it.
