The Sands $5 Arodie comes to mind. I've seen two of them sold over the years, one went for beaucoup bucks on eBay over 20 years ago and the other one was from Howard Hughes estate (allegedly) and sold recently with two other old $5s for over $21K (plus a buyers premium) on Heritage Auctions...That’s about the price I would expect for that chip. There are even more expensive singles, but not many.
I gave realistic offers on a couple of the chips from that seller. He/she responded back with ridiculous amounts and said they enjoy listing at super high prices because it pisses the “good old boys” off.To be fair to seller, that Sands chip is incredibly rare. An old price guide says $3500-4000 and "unique", Chip Rack says "* no market" which means the sky is the limit. I do think, however, that $12,500 is optimistic.