Spydies are typically one of the first brands to either go up, or down in price for the collectors, depending on the economy, and other variables. The rule is
1) when I have money, so does everybody else. Prices on models I want go up, and also become the "knife of the month", with bidding wars, snipers come out to play, etc.
2) When I need to sell a few knives everybody else is broke, demand is down, and the knives I want to sell were hot last month, but not now.
That's just how it goes. In the long run, over decades, if you don't lose money, you're doing ok.
If you gain money in the long run. You are lucky and smart. Should consider doing this for a living. Of course that would take all the fun out of it.
Face it, If you owned New Graham, would you get as excited about the ZDP Lum? Joe