Hi John,
I will try to answer your question with my opinion. When someone sells an expensive chip for a sum of money greater than what can be considered average, I believe the seller has a responsibility (an implied warranty) to the buyer. The responsibility via rarity is reflected in the price requested. In example, if I ask $1,000 for a chip and a week after I sell it a quantity is discovered that is great enough to force the market price down to say $500.00 - it is my opinion the seller owes a refund and/or credit to the buyer for the drop in market price within a reasonable time after sale. Let's say 30 days; however, it could be less than 30 or maybe 60. It is also my opinion the time frame, quantity found, etc., unless agreed upon prior to sale, rests with the integrity of the seller. It is also my opinion a seller has an ethical obligation to make a buyer whole in circumstances where the buyer depended upon the "good faith" of the seller as to quantity available, description of condition, and any other stated and/or implied assurances. Best, Jim