Interesting, because I've been looking for something too, as I acquire more knives. As you mention "display / store", they are two different things. Some you want to lock away, or to be out of sight, and others you want to look at or be able to grab in an instant.
So 2 ideas I stumbled onto just yesterday as I poked around town in the local antique shop. There were 4 antique silverware cases, for $10 each. They have slots in bottom, and little straps on the lid, and seemed well suited for knife storage. A decent one on auction sites seem to run $30 to 50. Most of them get scratched up on the outside, but can be refinished. He had a pretty nice one that I'm gonna go back and snag up for ten dollars. Cigar humidors work well too. I got a wooden one a while back and made a gun box.
So I left the antique shop and went next door to the mom & pop hardware / plumbing store, to get their calendar I use every year. Luckily, my ability to BS with anyone about anything sometimes pays off. I was eyeballing the Case knives and moreso the old wooden display case, and telling the part time cashier how the old cases are hard to find. Turns out she used to own a jewelry store and has some locking glass topped metal framed display cases that she used for shows and travel. She said she paid $100 each, and is selling for $40 each. Grey felt inside. I may try to get both for a reduced rate. She had a pretty nice store, and I expect they are nice. I'm dying to see them, but have to wait till she brings one to work next week. If they're nice, I'll find out where she got them, and post pics. Sounds like it may work well on an end table to display a few, but still be under lock and key.
JT