A few more details:
The banjo was in a green cloth case. The banjo was built by Seeger as a prototype which was later produced and sold by the Vega company. It has the following words written around the head of the instrument: "ThisMachine Surrounds Hatred and Forces it to Surrender".
Perhaps everyone can pass this information on to their local music stores and pawnshops. Hopefully someone either return it or be found trying to sell it.