SfN: The history man
There are lots of shiny high-tech stands here selling equipment that can track the movement of lab animals or peer into their brains. Sitting a little oddly amongst them is John Gach's stand. He's selling old scientific textbooks, and is doing a very nice trade.
My favourite was his copy of the 1794 Zoonomia, in which Erasmus Darwin discusses ideas about evolution that later influenced his grandson's theory. It's yours for $1,750. Pricey, but there were others that would set you back more. A copy of a monograph by Sigmund Freud on child neurology, signed by the author, is listed at $5,000.