Best I could do. Looks like he was based out of Gadsden, AL.
Gadsden Times Newspaper.
And this magazine.
An instrument made by a craftsman with wear will still play better than a Chinese import that's brand new. As long as it's playable and stays in tune, I wouldn't worry about wear too much. Something that we always encourage newbies to do over in the saxophone subreddit is when buying a new instrument, try to get something that you can resell if you realize that the instrument is not for you. So it's kind of like a buyer protection kind of situation, especially if the auction prices end up similar.
You can get strings on amazon prime for like $3 shipped https://www.amazon.com/DAddario-EJ64-4-String-Dulcimer-Strings/dp/B01F7KMRG2/ref=sr_1_1?dchild=1&keywords=dulcimer+strings&qid=1588711826&sr=8-1
Even if the ones you're eyeing have good strings, who knows what kind of shape they're in or if they'll still be good after shipping.
What about something like this? Or, maybe one of those non-adhesive dash pads for phones, but larger?
They have a typical plastic pick point, and rubber grippy bit. The closer you grip to the end of pick, the firmer plastic part is. The grooved rubber bit keeps the pick in your hand if you get sweaty fingertips while playing. And you can flip the thing around and strum with the rubber part which is a nice muted sound.
If you are looking for a starter mountain dulcimer I suggest going this way with a kit. This was affordable and plays pretty well, though I would lower the action on the bridge if I built another one. if you are looking for a hammered dulcimer then that's a whole different beast. Listen to the advice from /u/TapTheForwardAssist regarding age, string replacement, and learning material.
There are quite a few mountain dulcimer players at EverythingDulcimer.com - I'm doing a few shows in WI this year, but I'm booked in September. You can hear, and download, some tunes on my Reverbnation page. I could perhaps suggest some folks for you. Good luck!
I have found these super helpful! It will seem on the simple side, but it does a good job on speed reading songs.
I don't have much specialist sheet music but I do have this one, which I'd recommend: https://www.amazon.co.uk/Middle-Eastern-Music-Hammered-Dulcimer/dp/0786671815 it was a surprise Christmas gift from a family member!