If you're talking about one for sale in the States, Bonehill targeted the American market pretty heavily in the late 19th century. They used more "modern" manufacturing processes--that is to say, more machine work--on some of their guns than did a lot of the British makers. Hard to say how much it's worth without knowing more about it, as well as the condition. Bonehill would be a good place to start. It's a well-known name and likely can be had for less money than more prestigious makers. If it's marked either "Belmont" or "Interchangeable", that would indicate that it's one of their guns involving more machine work and less hand work.
