They are onyx probably from Mexico. I find them for sale here in town from ~ $40.00 to $75.00 depending on the quality for a complete set, pieces and board. The problem with the pieces is you will have a real hard time finding a matching board. You may find one that is close, but not the same.
They are also non-standard pieces, so other than for show, they are not reallly that practical.
I found this article (below) here and bought from the company. I am happy with my purchase. I also bought tournament sets from Cajunchess.com and have been very happy. Good luck, hope my blip helps.
http://www.chess.com/forum/view/chess-equipment/confessions-of-a-chess-set-addict-long-many-photos
Found these at a thrift store (without the board, No info on the pieces or anything) And I was wondering if anybody here knew something about them?