$500 is a tough number for the Bambino but stuff is out there. "If" you can convince your work to fork out $650 (or maybe you can get it reduced?), there is a beautiful 1929 R316 Kashin on this very BST board.
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Just scroll down bit on the 1920s section. I was seriously thinking of buying it but I think it would be a great prize for your event!
Peace, mike