A single proof specimen exists. It appeared in the 1911 auction of the William Woodin collection, then remained untraced for decades. It was re-discovered in 1995 by Texas dealer Mike Brownlee. It showed up in an April 1998 pricelist by Eagle Numismatics of Humble, TX. Their asking price: $1.75 million. Sigh. It was in a PCGS PR64 holder.