What is a double barrel 12 gauge Ithaca gun company serial 391823 value?

With the serial number that you provided,your Ithaca double barrel shotgun is a Flues Model shotgun that was produced in the year 1925.As to the value,that would be difficult to determine with Ithaca making many different Grades of the Flues model shotgun,along with many different special order features that could be ordered.I would have someone that is experienced with double barrel shotguns appraise your firearm.