50-100 USD
An early model Lefever single-barrel 12-gauge shotgun with a 30-inch plain barrel can be found for sale online for $300. This is the price for one that is in excellent condition.
Maybe 150 or so
Are there any other markings on the receiver or barrel? I have several listings for "Price" shotguns made by W.H. Davenport Arms and J. Stevens Arms & Tool Co, but nothing with Mo N or No N.
Not enough information
50-100
Around $50-$75. sales@countrygunsmith.net
Normal price for a store-brand 12 gauge is $90-$150, but if it is really in 100% new condition it might bring a bit more.
500
50-100
50-100 USD
the price
There were many thousands of the Shapleigh King Nitro 16 Gauge with a double barrel. For the most part, they are worth about $50 to $100 depending on mechanical and finish condition.