I just found a Sigma DM 5 (looks like Martin) in Moms closet where is has been for at least 30 years that I know of. It has slight scratches on pickguard but other than that is looks brand new. Even the original chipboard type case is pristine. Does anybody know its value other than just to keep and play. Is says made in Japan inside along with a #S91356. If I did not know its true history it could be mistaken for brand new. The binding is white and black, and headstock says SigmaGuitars est.1970....any input is appreciated!