Impossible to attempt to answer with no information on make/ model. A serial number is NOT unique to only one firearm in the world.
35-100 USD or so
25-50 dollars
3'000 $
10-100 USD or so
Blue Book of Gun Values
Need more details
To determine if a specific serial number like 064867 exists on a Jukar Spain .45 caliber derringer, you would typically need to consult records from the manufacturer or a firearms database. Jukar manufactured various models, and serial numbers may vary widely. It's advisable to check with a firearms expert or a collector's guide specific to Jukar firearms for accurate information.
No serial number provided.
We need the model and condition, not the serial number.
Not with just the serial number.
The maker of your Derringer is no longer in business. Sorry-
No way to answer without a maker and serial number.