[MarlandS]

here's what I have for Nitro Hunter, single shot , made by Crescent for H.D.Folsom for Belknap Hardware Co Louisville KY

double barrel made in Belgium and imported for sale in the USA

co's are defunct.

so is it a single or double then an answer can be given for the third question

 

[MarlandS]

$50 - $100 would probably catch most examples.