There is a specimen of a Barnes & Mullins pre-Abbott Amboyna in captivity in Birmingham Alabama and up for auction at what might be too high a price for the condition it is in. The wood seems rather plain in the photos and I wonder if it is something else other than amboyna wood. Still worth a look, to get a sense of history.
http://www.ebay.com/itm/Antique-Banjo-Rare-Barnes-And-Mullins-pre-1...