I like to display my models in old china cabinets. They are available for free to cheap. This is my main display case, downstairs in my office. I have my best stuff on display here. Due to the height needed for displaying glasses and platters, the 3 shelves are far enough apart to add a shelf between each, doubling the capacity to 6 shelves. China cabinets usually have lights and glass shelves so they're pretty much made to order display cases. I paid $100 for this one at a consignment furniture store.
Here's my original display case / china cabinet that I've had in my model room for 24 years. I got this one free when a relative was moving. This is upstairs in my model room. Like the other cabinet, I intend to add an extra shelf between each existing one for a six shelf capacity. Not much in there right now.
Here's a display case that holds some of my old custom collection, also up in the model room. My wife had this one for years, when one day on my way home from work, I saw a dark wood one just sitting at the curb. I had the Caravan so I stopped and grabbed it up. My wife liked that one better, so she traded me!
In this photo you can also see three wall mount cases that I have yet to use. I also have a small store display counter out in my garage. I got it for free, another curb find, but it doesn't have any shelves. Eventually it will go in the same general area as the last two in the model room. We are in the process of selling my in-laws house so I may come into a third china cabinet.