Appears to be missing the screw on the hammer too. Soaking the bayonet in Kroil for a while should get it off of there. Might even give it a week or two to soak in if it does not work overnite. Then tapping it with a plastic or even rubber mallot might break loose the rust or whatever is holding it in place. I don't know what the handloads are, but if they are not something that is a blackpowder equivalent for pressure in a gun in that condition, yea, I would run away too. Really nice ones will run over 1000$ nowadays, but rusty beat ones are alot harder to sell. You might only get a few hundred from a buyer or even less from a dealer if he makes an issue of the condition. Not the worst I have seen for sale though. Just was apparently not stored well for a long time. But a hundred years ago surplus trapdoors were worth peanuts so got no respect?
Your gun is like your nose, it is just wrong for someone else to pick it for you!