I store and "display" the ones I am not using in a rubbermaid tub (this includes customs). At least I know where to find them if I want to fondle one. Knives that have no boxes or other case, are often stored inside socks that have been taken out of the using rotation. The knives I use or are likely to use are on a shelf in a metal cabinet which contains much of my 22 ammunition.
If I were to display some of my knives, I'd probably pick up a couple aluminum cases that are often used to display firearms at gunshows. I believe most of these have plexi-glass or glass tops. I have little interest in this. I seldom even take pictures of my knives although I do play around with the camera from time to time.