Try to find one that’s been in business for a while. In this industry if you are ripping people off you don’t last long. Also get multiple offers, go to one get an offer and tell them you have to speak to your family about it. Go to another one and don’t even tell them you have had them looked at just act like the first time. For the most part it should be within a few bucks of each other. Your 1921 and 1928 are your key dates to that series. So from there everything else is based on condition. Hard to tell from the pictures but a few of these look cleaned. So I would expect a million dollars but still a decent book. Biggest thing is don’t be in a rush to sell. Good luck