I'm always looking for a guitar, banjo, mandolin or ukulele that was American-made before 1960. Mostly, that means old Martin and Gibson acoustic guitars (pre 1960), or Fender and Gibson electric guitars and amps (pre 1970). Gibson banjos (pre-1940) Vega Fairbanks 5-string banjos (pre 1920).
There are certainly others that I'd be interested in, for example, old guitars by Recording King, Stella, Kel Kroydon, Weissenborn, Trujo, SS Stewart, Cerrito, to name a few..
I get them restored if they need it (Even if they are near death, seemingly beyond repair, they can likely be saved and brought back to playing condition.) and I sure love to play them and hear what they have to say.
My website, GrandmasGuitar.com is back up and running. That has lots of info on old instruments and how to value them.