By the serial #
What does this gun sell for?
Impossible to answer without the serial number
1905
This gun was made in 1989
Blue Book of Gun Values
If the shotgun is a hammerless double, it is a Baker Model produced in 1899 (per Dixie Gun Works, Ithaca Serialization Guide) That serial should be a 1926 production NID. sales@countrygunsmith.net
Try Midwest Gun Works.
The serial of you Parker shotgun did not print in your question. But to find a date by serial number, there is a Parker Gun collector website that has a list of serial #'s and date of manufacture. The website is : http://www.parkerguns.org/
The gun was made in 1931
This gun was made in 1942
The value of any gun is based on make, model and condition. We cannot tell that from the serial number. You need a hands on appraisal. Take your shotgun to a reputable gun dealer or gun show near you.