My pocket knives, I usually go for the discontinued but popular types and have found they do appreciate in value over time.
Small Tactical Gentleman’s Auto by Benchmade, blade length is 1.98" (under 2") making it pocket carry legal.
Spyderco Lum Chinese Folder, flat-ground blade made of ZDP-189 stainless steel, about as sharp a blade money can buy.
Spyderco Kiwi Smooth Red Bone, the best "whittler" I've ever owned.