Let me throw in my two cents (which is worth less than 2 cents).

An item is worth what someone is willing to pay for it. When someone bids on their own item, no matter if it is $2 or $20k, it is misleading the market.

The item really isn't worth 19k in your above example...no matter what the outcome is...if the final bidding was meant to have been 18k, that is what it is.

Like stated previously...set a reserve if you are afraid the final price won't be to your liking. It is legal, and does not fraud the market out of valuable data.

The AH hypothetical is not realistic: no consignor who can do math is going to shill an auction already sitting at 90% of past results since it would cost him somewhere on the order of 18% of the value of the lot.

Shilling in an AH would be attractive when the price is way below market and the seller is going to take a giant loss. I'll give you a real world example: Heritage Auctions. HA does two interesting things: it expressly allows consignors to bid into their own lots in return for paying the BP if they win, and it holds unsold lots open for some time as BINs for the minimum bid. I sold a bunch of stuff in November. I did not bid into any of my lots in November. Two of my lots, however, which I was into for ten times the opening bids, were offered as post-auction BINs. I opted to exercise my consignor's rights to BIN them [at the cost of the BP] and avoid taking a 90% loss. The cost to me was effectively 20% of 10% of the cards' value, i.e., 2% of the value of the lots. It was worth 2% to me to take the cards off the market rather than see them sell at throw-away prices and net practically nothing.

This isn't the same as shilling--shilling by definition is illegal and not allowed under the auction rules--so not a perfect analogy, but it is the same financial calculation. To me it was worth 2% to hold my items back. If the cards were at 70% of what I felt was market price I probably would not have gone back into them.

One further note: this whole idea of 'market' is an artifice. We don't have the theoretically perfect flow of information and participation that the model assumes. With all of the auctions around plus eBay the reality is that lots of collectors miss lots of items, which sell for a lot less than they would have otherwise. If information and participation were perfect it would not be possible to flip cards for a profit. I have often had cards go begging on eBay or at auction then suddenly take off and sells in competitive auctions. No rhyme or reason to it, they just got found by the right bidders.

Good to know Heritage Auctions allows you to shill your own items.

What about the auction houses who were in cahoots with the consigners and wouldn't charge the juice if the card didn't hit the hidden "reserve" agreed to beforehand?

Don't underestimate how brazen some of the consigners/fraudsters are/were. One guy on Net 54 even told the various auction houses that he wouldn't consign his large collection to them unless they agreed to let him shill his own lots. Naturally, Mastro agreed to that demand and, naturally, even bid on his lots for him.

To paraphrase the great showtune

But where in the world
is there in the world
a man so corrupt and impure?:D

in your situation you are effectively allowed to do a 'reserve' at a cost....as a bidder im ok with that or even if the shiller has to eat 20% on a 'win'

as to market.....there are certain amounts given a few months we know a 'safe' amount of what we can get for certain cards...a 1952 topps mantle psa 5 any example non qualifier if not fake etc I think anyone would pay 14k for...maybe it can go for more and tons of examples have gone for more, and maybe there was shilling to get to 20k many many times..but cant we agree that shilling wont impact that card being worth 14k? wouldn't everyone on net 54 agree the 'market' would be safe to pay 14k for....the thing with fighting 'schilling' is you cant win.cause the seller can always have a 'friend' that knows the card is worth 14k pay 14k for it..and it magically goes back to the shiller....

I think this shilling is really just a passive aggressive reserve....what a card sells for to me isn't what its worth all the time anyway to the next buyer...if a card sells for 20k then its possible the only buyer wlling to pay that price just bought it,..now that he is selling it..it has a good chance to go for less as he is no longer in the market and he may of been the one bidding it up with potentially just one other bidder to that amount in the first place..

..to me the card is now'worth' something less than 20k...so I don't view past results like everyone else ..I like to see many multiple buyers bidding above a price point etc..