Can't be answered without knowing who made it, what caliber/gauge, if its a pistol, rifle or shotgun. Even then, the records may not exist/be published.
If everything is there including the rear Peep sight and it's in decent shape anywhere from $150.00 to $250.00. There is one at Gunbroker.com right now with an asking buy it now price of $300.00. I doubt that it will sell for that much but you never know.
my son just purchased one this past Sat. for 300$ with a Leupold 2x7x40 shotgun scope. the gun is in mint condition and has been fired very little. the scope was also used and I think he could have bought the gun alone for around 200$ we knew nothing of the gun til we ran across it.