You might be surprised at some of the knives that have increased in value significantly over the past ten years. Once Schrade went bankrupt, the aftermarket prices of Old Timer, Uncle Henry, and other Schrade products skyrocketed. It's not uncommon for Old Timer models to have increased 400% from 2004 closeout prices to today's collector values. And Old Timers were produced by the millions! Not at all rare, just famous. Even some of the lowest-end Imperial knives might only be worth $5 today, but that's an incredible increase in value since they sold for only $1.39 when new (closeout pricing).
Bark River knives is another good example. Some increase in aftermarket value is undoubtedly due to the increase in new knife prices, but some low production models have doubled or tripled in value, based on recent auction sales. These weren't common knives sold at every ACE Hardware in the country like Old Timers, but they certainly never cost $450 either.
Guess what an Effingham Ek is worth today? Wish I could have bought a whole truckload when they were closed out for $30 each.
Spyderco Q. Camillus Terzuola CUDA. Discontinued models from Buck, like the 120 General. Check the difference between recent Boye Basic ebay auctions and their original catalog prices. Etc., etc., etc.
Naturally, I could name just as many low-priced and high-priced knives that have stagnant values or no collector interest what-so-ever. Take the Camillus Becker knives for example. They were extremely popular and in short supply even before Camillus went out of business, but they haven't increased in value at all since then. I could also name a custom maker or two who put out a decent product but are now shunned by collectors and knife enthusiasts because of a collapse in their personal or business reputation. Or interesting well-made knives that are passed over by collectors in favor of new production knives that use higher-grade materials.
That's my point, future values are impossible to predict, and are dependent on many factors, each of which is equally impossible to predict. I'm certainly no expert at collecting either, but it's ridiculous to say that only upscale knives increase in value, or that buying super-expensive knives is a guarantee of increased value.