I have bought a lot of stuff at estate auctions. Yeah, a generic estate sale will not generate a lot of money, but if you have serious art (i.e., it would sell to more than a local audience), it can bring in quite a bit. I saw an Alan Bean (the astronaut) painting at one; ended up going for over $30k. And the estate gets all of that; the auction house charges a premium (in this case, 25%) paid by the buyer, but the official auction price is what the seller gets.