The value of an Iver Johnson Arms and Cycle Works firearm, such as the one marked "J8541 Pat Pending Nov 17, 08," can vary significantly based on its condition, rarity, and historical significance. Generally, such firearms can range from a few hundred to over a thousand dollars. For a more accurate appraisal, it’s advisable to consult a firearms expert or check recent sales of similar models. Collectors often place a premium on original condition and provenance.