You didn't actually specify if you were looking for cabinet type cases or just cases for display of one or two models for each. For the latter, I have got cases at Hobby Lobby and the same type on Amazon. They are approx 15" x 7" by 7" high and work well for 1/35 armor.
If you're one of "those guys" who has hundreds of complete models and hundreds in the stash, then I guess you can ignore this post. ;)