Re: Henry Elwell Dbl BBL Shotgun Value
Larry, except for those by a few renowned makers, there's little collector interest in percussion shotguns in USA, and value would be as a nice decorator's wall hanger, or possibly to a black powder shooter who wanted to fix it up.
It has a few issues, eg. mismatched hammers and the repair to stock you mentioned, and looks like left nipple probably missing or broken off as hammer is too far forward. My WAG of value it would bring at an auction would be $200 plus or minus.