Cases aren't so much of a product that you see hundreds of case manufacturers like you do with module manufacturers. Off the top of my head, only about two dozen firms specifically making cases come to mind, making it simpler to shop for cases via the various online shops. If you tool around 5-6 of those, you'll wind up being able to comparison shop the majority of Eurorack cases and power solutions available.
Also, having a look in the Eurorack section under "power" can often provide useful clues as to who's also making other power products and, by extension, cases. Not every power supply manufacturer does, but a large percentage do have cases as part of their product lineup.