Where can you buy saguaro cactus pieces?

In the United States the saguaro grows naturally in Arizona. However, it is illegal to remove a saguaro from the desert without permission and only for a legitimate reason (eg: The cactus is falling into a roadway or home or needs to be removed for construction.) It is also illegal to remove even the dead wood from a saguaro cactus from the desert, The only alternative would be to purchase a saguaro from a nursery, let it die and decay for a few years and then remove the dead wood pieces. Considering the high cost of a live saguaro from a licensed nursery, this does not seem to be a viable option.