Vietnamese mesotheles: segmented trapdoor spiders of the ancient lineage, hinged doors, radiating triplines, and the body plan that predates almost everything else with fangs. Like all mesotheles they lack functional venom glands, which removes the question that structures every other spider entry.
The keeping is deep, stable, humid substrate, a burrow established once and held for years, and a door as the entire visible animal. The purchase is custody of deep time.
Vietnamese supply barely exists, captive breeding rounds to zero, and the trade consists of rare singles priced to the audience that collects lineages rather than displays. Within the mesothele shelf this is the mainland Vietnamese entry alongside its Chinese relatives, all of them scarce, all of them traded on what they are rather than anything they do.