Tonight on Antiques Roadshow, they showed a 00042 Martin. The guy didn't play it at all but he said it was built in 1938. (he said Martin made them from 1913 until the 1940s, I think.) He said the top was Adirondack Spruce, which he said was no longer available. The guitar appeared in good shape and was supposedly a one-owner, belonging to the widow of the man who had bought it new in 1940. She said her husband had been a cowboy and a musician, who had strapped the guitar to the back of the saddle.
The appraiser estimated its value from $20,000- 25,000. I would have loved to hear its tone.