For those who are active and long enough in this hobby, you would have probably identified some who goes into auction group, get cheaper corals and sell at "retail price" of a more exp lfs.
This cycle is not new and was partly the reason why hobbyists sales and trade of corals were banned in the past.
Nonetheless, buyer willing seller happy. Just dont spoil the market until another ban comes about.
For people who are not convinced about the item, ask to view to avoid discrepancy. If his rock is really huge or quality is really good, then the price at this current crazy market rate can be justified.