A.k.a. The Carvana model. This is what Carvana and other "no-haggle, no-test-drive" startups are doing with the whole used car market in many areas. They aggresively buy up all the used cars in an area (or at least as many as they can) from dealerships and private sellers in order to make themselves the only entity with used cars for sale. Which they happen to be selling at 20% above true market value. But hey, you c…
If carvana is not providing that value, then there should exist plenty of sellers that want a piece of that 20%, such as car dealerships and individuals themselves.
This is a market with plenty of buyers and sellers, and low transaction costs. I see no reason why Carvana would be able to corner it.