Vintage Case knives can vary widely in value, which is determined based on rarity, style, size, age and composition. The condition of the knife is also very important. Case knives that have the original packaging and have never been used are worth more than one that has been used or is missing the box. Magazines such as "Collectors Weekly" sometimes have articles on vintage Case knives.
"Blade's Guide To Knives And Their Value" is available for sale at knifeworld.com. The guide is updated regularly with values based on condition and age. An antique dealer can help determine the value of a vintage Case knife. Knife shows and exhibitions often have experts that can assess the value. Online auction sites such as eBay have listings of antique Case knives that suggest a general idea of the value of some knives.
Online knife enthusiast sites such as allaboutpocketknives.com offer advice on identifying what type of Case knife you have and the year it was produced. Sometimes knives have a higher value than expected due to sentimental value. Online retailers such as collectorknives.net can help determine the value of a knife. The value that a knife is purchased for is often lower than the retail price so the seller can make enough profit.