Our forefathers wrote into our laws the right to keep and bear arms. I think no permit would be required unless your local government requires something special. Even then, that would go against the Constitution IMO.
Guns are like guitars in value. Old guns are valuable but only to those who are interested in guns. Just like old guitars are valuable but only to old guitar enthusiaists.
I wouldn't even know where to begin to find someone that could properly appraise a gun.
My guns will go to my children. They were passed to me from my father who inhereted them from his father. I don't shoot guns either. I don't hunt . I was once a policeman though. My guns are heirlooms moreso than weapons. I gave one to each of my sons last year and the same this year. I will give them one each Christmas until they are gone from my possession.
I may keep one to shoot my banjo though if I don't learn how to pick that scoundrel.