Economists have a fancy term for determining what something is worth -- "price discovery". It affects things like stock prices, oil / commodity prices, and pretty much anything else that trades or barters between individuals. Largely a matter of supply vs. demand, prices jump around on a rational and sometimes irrational basis (e.g. toilet paper, at the moment!)
For chips, the standard answer has been that a chip is worth what a willing buyer & seller say it's worth at the moment of transaction. While we have some chip guides & historical references, I'm sometimes surprised to see what chips sell for in Chip Chat or eBay auctions, and elsewhere ... both on the high side and low side.
With that as an introduction, here's a recent sale on eBay that caught my attention: A $2.50 snapper from Barney's Casino - Stateline. It's a tough chip to find, full value around $500. A pretty chip in excellent condition, offered by a reputable dealer. In this case, Mitch got full price, with 2 buyers going all-out.
However, note that if just one of these 2 bidder's had not participated, it would have sold for 1 increment above the 3rd place bidder, or at about $160. So ... is it worth $500 or $160, or somewhere in between? Depends on each transaction.