Aaron, I'm not sure where the Ivory was sourced from. There was and still is a lot in this country that gets traded around. Also, seems like I remember reading that they occasionally get some new ivory from herd culling, but has to be with the right and proper documentation for it to be legal.
That is indeed a gorgeous brush! Is it a breach of forum protocol to wonder aloud what one could expect a real ivory brush to cost?
Plisson has one of their smaller brushes in an Ivory handle for about 12097.57 the other day, given the exchange rate of euro to dollar. Domestically, one can do better a WHOLE lot better. Getting stuff like that here from Europe is, well... getting stuff here from Europe. I'm not sure how customs deals with Ivory exporting and US Importing it. Here, in the U.S., it's a matter of buying and one sending it though the mail. Most of it here is well documented to be, well, here.
Congrats on a fine brush. There's an organic connection to genuine ivory that's difficult to describe. One must feel it. Enjoy.