I don't offer a valuation without a personal inspection - there are many others who will cheerfully do that - without any knowledge whatsoever.
The piece 'looks' to be in good condition - use your own skills and evaluate it like any other used revolver - check for finish, lockup tightness, condition of the barrel, and so on and so forth.
The Pepperbox - if working - has a minor appeal to some.
If the guy is emailing you, then he 'wants' to sell - see what his best 'cash' price is and go from there.
Scouts Out!