[Most] everyone knows that I bought 38 of the only 50 $25 chips ever produced for a particular small town casino with a book value of Z2 for each chip. I haven't heard of anyone else owning one of the remaining 12, and maybe no others exist. At the time I (and others) were bidding on them, the discussion was "welp, I guess those are worth $100 now". I've sold one (above Z1 but below Z2 price) and traded 2 others for Z2 value. I still have the rest and you don't see me in any hurry to unload them, so in spite of the fact that a "hoard" of 3x the 12 possible chips were found, the value did, and will remain, high. At least until such time that someone offers me a 6-liter solid gold amulet filled with jewels (or equivalent) to buy them from me. Would I give a big discount off of TCR if someone wanted to buy them all? Sure I would. But I'd rather put these chips in the hands of other small-town collectors in return for Z2 chips that are still on my list.
This may very well be what the buyer is going to do with them. Trade them out one at a time for high value. If they remain impossible to find, then the book value (or close to it) will likely be within reason to fellow collectors. If they are appearing once every week (Bar of Music, anyone?), then one can wait for the eager beavers to pay the highest prices and then you can get in on the cheaper ones as the market dries up.
Anyway, that's my 2 cents worth and I offer an opinion-back guarantee.