Following this line of logic, I think small shops are the only ones with aligned incentives. A single person or small team is never going to run out of people to sell to, provided they can ship far enough. Of course just being a small shop isn't a guarantee of quality. Probably the opposite— there's a lot more variability between good and bad between small shops, or even between different batches from the same shop. But at least the possibility is there. So I guess that points to… something like etsy? Or local, if it exists in your area.