If you are talking about that Case Dale Earnhardt two-tone Russlock, you had listed a couple of times, then yes, you are going to have a hard time selling those anywhere. Any of the "affiliated" knives are going to have a lower demand. Johnny Cash, Ducks Unlimited, Carhartt, etc. And add to that it was dual colored, and a Russlock.
So you'd have to find a Nascar fan who happened to like that particular driver, who was also into Case knives, who likes the somewhat odd Russlock pattern (I like them personally, but I have enough already), AND who didn't already have one of that particular knife. A buyer like that might come along and really want that knife, but you might one see one really interested buyer every 6 months.
I am a member of the Case Collectors Club forum and one of the guys there who was a huge Russlock collector decided to start selling off some of them. I think he lost money on every one of them.
So, if you are planning on buying for resale, pick: popular patterns, in popular handle materials, that appeal to a wide range of buyers (so stay away from specialty/affiliated branding). Plus, Case knives are generally in the $30 to $50 range new. Just shipping and Paypal fees will kill you there. $5 shipping is 10% of the cost of the knife.
If you want to try to break even or make a profit, then you need to be in the high dollar knives - like the Case/Bose annual collabs, and be willing to hold onto them for YEARS until the dealer stock is completely exhausted. And even with those, I still see them selling below original pricing because of motivated sellers and not enough people who want to pay $300+ for a slipjoint.
Anyone who tries to make a buck on selling knives needs to know the market VERY well, and be routinely buying out entire collections from uninformed widows at rock bottom prices.