Early 19th Century Biennais Paris Goldsmith Hidden Compartment Desk Box

This is a beautiful box from Paris by renknown Goldsmith Martin-Guillaume Biennais (1764-1843).  Inlaid brass with a shield insignia on top.   There is a hidden bottom compartment that opens when you stick a pin down into one of the holes on the rim.   There's also a compartment that opens inside the lid but the mechanism to reliease it (assuming it's the second hole on the rim) isn't working so it remainds closed.   The lock works great!

The box has a crack the length of it along the top.  No other damage and in otherwise great shape.  It measures approximately 10" long x 6.5" deep by 4 1/4" tall.  

I'm looking for a fair market value as the piece is going into an auction.   Many thanks!!

Fair