You will have to provide the name of the maker.
14 gauge has been made.
what is a dixon falcon 12 gauge shot gun made in Spain worth
Brazil 12 gauge single shot gun
Blue Book of Gun Values
How would we know?
Impossible to answer without knowing who made it.
I believe that the Plymouth side by sides were made by Cresent Firearms.
$20 US if your lucky
$175.00
Inexpensive; late 1800's made.
20 gauge
I would start my search at numrich gun parts corp.they can be found on the web.