Ravine trapdoor spiders, and the abdomen is the entire story: it ends in a hardened, truncated disc patterned like a seal, which the spider uses to plug its burrow behind it. Nothing else looks like this.
Chinese, Vietnamese and southeastern US species circulate. They dig a silk-lined tube, cap it, and stay in it. You will essentially never see the animal, which is worth understanding before purchase.
Wild-caught Asian material dominates supply and arrives irregularly. Captive breeding is close to nonexistent because they are difficult to sex, difficult to pair, and slow. Prices are firm and availability is the real constraint. Expect to wait rather than to negotiate.