Spesco did not make firearms. They imported them.
Blue Book of Gun Values
Blue Book of Gun Values
Try the Blue Book of Gun Values
Blue Book of Gun Values
Blue Book of Gun Values, proofhouse.com
Blue Book of GUn Values can help.
Try Blue Book of Gun Values
They will have "Made in Japan" on them somewhere. Value will depend on exact configuration and condition.
Check out a copy of Fjestad's Blue Book of Gun Values in your local library or book store. It will give you current values for old Marlin pump action shotguns.
Not really. Your best bet is to check the online auction sites such as GunBroker.com.
You will need to look in old gun catalogs, Blue Book of Gun Values, etc..
A few hundred to multiple thousands of USD depending on EXACTLY what you have and its condition, accessories, box, papers.