Ebay is actually a bad place to get an idea of prices. Best is to look in knife books and talk to lots of collectors. Because on ebay, asking price and even sold listings wont give you true value. People over and under spend so easily. We are talk actual value, not what you pay for the thing. Then ebay is a great place to get an idea. Like the whole of collecting anything, knowledge comes with experience. Not talking about you know what.
Willy I’m not following your logic here. True value is what someone is willing to pay. If several someones are willing to pay that price, even better.
Book values however are static. They are whatever the author fixed them at when the book was written. True values fluctuate over time. Knife values are dynamic. They change depending on the economy, collector fads, availability of raw materials (stag, pearl, etc), laws (ivory), inflation, and other variables.
A recent example: Case 63047, 1971-1979 dotted mint to near mint condition. Sargents Premium Guide to Knives and Razors
7th edition, published 2008 says value is $60. Pfeiffer’s Collecting Case Knives
2nd edition, published 2015 says value is $65. However three of them have sold on eBay in the past couple of weeks for between $42 and $48. So are they currently worth about $45, or $60, or $65?
EBay provides a wide audience of potential bidders, so its sold listings are a good resource for what buyers are willing to pay (in other words the true value) at the time of the auction. In other words, it’s a good place to get an idea of current prices. I do agree that eBay asking prices aren’t a good resource - you need to look at sold listings. On the other hand book value is the author’s educated opinion at the time the book was written - likely years ago.