Source for older knife prices?

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I have been away from the knife scene for some time, and have a number of knives I am considering selling if the price is right. These are older, discontinued models from major makers (Spyderco, Ontario, etc.) but old enough that I cannot find anything about them on the web or on eBay. Anyone have a clue as to where to find such info? I live in the Twin Cities area, if that makes a difference. Thanks in advance for any help.