Segmented trapdoor spiders, Mesothelae, and the most primitive living spiders on earth. The abdomen retains visible segmentation that every other spider lineage lost.
They build a silk-lined burrow with a trapdoor and radiating trip lines fanning out from the entrance, and they strike through the door when a line is touched. Southeast Asian, slow, long lived, and almost never visible.
CITES Appendix II, which restricts international movement and is the reason availability is thin and irregular even though the animals are not especially difficult. Captive breeding is rare. Prices are firm and the market is small enough that a single importer's decision moves it. Buy when you see one.