Okku I believe that ultimately a chip is worth whatever a buyer is willing to pay for it.. I agree with most all of what you said but there is one thing I have to disagree with, and only to an extent, what someone paid for something as there are to many variables.
Valuation of chips is a tough thing for sure, but recent sales of a chip and historical sales have to be taken into account broadly, since its a current topic lets take these Cotton Club $5 chips, historical sales of the chip have seen from $2400/chip high, and $800-$900 frequently, these chips have been in the "book" as a Z1 (8-11 hundred) for quite some time with the notation that 2000 were made, Now, a rack surfaces and sells for $3000 on a platform with a minuscule view (hundreds) as compared to eBay (millions), Sold 3K on PCF, how do we now value the chip?, is it worth less because there is a rack? yes that factors, is it further driven down because we know the unusually low price paid for the rack? I'd have to say NO, why? because the price paid was skewed by the fact that there was very few informed buyers competing in the auction.
At PCF there is far to many undo influences, such as the admin restricting who can freely bid. There are people like myself who have been restricted due to personal issues the admin has with me (but there is obviously ways around this), other bidders who for one reason or another could not bid due to posting requirements to use the service, and lets not forget the tumultuous relations between "Sets" and "singles" collectors that have come to be due to a handful of people on both "sides" of that causing a further audience limitation (a topic for a whole different thread), but 100's of less participants. This drove the possibility of those chips selling at a "true value".
Now if on eBay (wide audience) or ChipChat auction (focused audience in the high end arena) I believe theres no way 3K would have stood. But I say that the skewed sale at 3k was a highly unusual price and factoring value simply because that price is known is in error. If everyone is looking for a Riviera $5 brown balloon chip in mint condition with a high value sees that one paid $25 from an uninformed seller do you now get to tell the new owner that his chip is now worth $100 bucks because you know what he paid for it? NO you don't because there was a very unusual circumstance. If you were the new owner looking to sell it you would contest that because we "Know what you bought it for" isn't a factor.
Now add to that some crack pot who for whatever reason may not like you decides to make a public case that because you bought it for $25 your chip is worthless now. That just idiotic. There is many examples of chips that exist in quantity (many 1000's) that sell for upwards of $200 a chip (say Blurple NL $25's, Mapes $100's etc.) but no gripes there. I suggest that certain collectors try any avenue possible to lower the value of chips based solely on their opinion of the owner, jealousy of a find, or want of the chip which should not be a factor. Ours is a small (drop in the ocean) hobby which leads to bad acts from influential or self proclaimed "experts" affecting values with biased information and statements.
Anyway, in the end and with many factors not discussed in my long winded
Blackbeard book here, a chip is worth exactly what the seller and the buyer agree to and is based individually from buyer to buyer. One chipper asked me "How are your beloved Felix chips" in a feeble attempt to insult me, and "Why not put a cotton club chip on ebay and let it fly"?, My response to that? Do you want a mint condition Felix? Do you want a mint condition Cotton Club? and at a cheap price, I suggest you buy one from a willing seller. at a cheap price.
As much as I love chipping I have to say the personalities in this hobby are definitely diverse from great chippers to, well, maybe we can just say "Not so great".