Guild of American Luthiers:
I have been a member on and off for 10 + yrs.

Classical Guitar Delcamp:
Useful forum for musicians and luthiers alike
Buttton
Buttton
All Strings Nylon
Supplier of Tuning keys and Strings and other misc. materials.
Luthiers Mercantile:
Main source of wood and tools and everything in between.
Buttton
Buttton