I sell insects that I personally collect, and miscellaneous items, mostly small collectibles, pins, buttons, some books, a bunch of USGS government bulletins and the like relating to mining and minerals, and...
... a unique 500-volume set of the Cactus & Succulent Society of America's Journals, from 1929 through 2011, bound in green leather volumes. Not many of them around. Every journal / magazine from that 83-year time period is included.