Hamilton is an old school remainder dealer. They had a great mail order catalog in the pre internet days. I remember buying the WW2 ace pilot Joe Foss’ autobiography there for $3 new. Happy days.
I still send in an order from their paper catalog(s) once or twice a year. On a side note, one of my brothers has an autographed copy of Black Sheep One, which he bought from Pappy Boyington at an air show.