I've seen this before, or something incredibly similar, and remember thinking it was plaster.
Also seemed to have been artificially " weathered " as if to appear old. Almost an excavated look but something not quite right.
It could be the Bo.. is Borrel, for Alfred Borrel, a French sculptor who died in 1927 but better known for coin and numismatic designs. Possibly this is an " after " example, a copy of one of his busts or made in his manner. It could of course be used to help sell the bust !
Anyway, worth more than you paid but not much more even if a period piece. Cleaned up, i could see someone paying three times as much on a stall.
Keys Auctions sold something similar in 2006. Good auction house.