As a cheapskate, I'll report that standard commercial half-gallon fruit drink or milk containers -- the kind that used to be made of waxy paper and is crimped at the top -- is just the right size for lots of floppies.
I recommend cleaning and drying very, very thoroughly. I understand juices are acidic, that some metals don't tolerate fruit juice well, and even low-quality fruit drink might have 10% juice. I don't know about milk. I assume it's all bad, and I assume my floppies (made with metal sliders and a metallic media coating to provide magnetism) will be in there for years, and treat the containers accordingly before exposing floppies. But then you'll never have to clean a box again.
Not only are fancy floppy cases overpriced (compared to 99 cents for a half-gallon with days of vitamin C or D), the fancy cases are bulkier. Drink containers waste very little space when full. You can cut them down to take smaller piles of floppies, and that can make sorting floppies into separate containers easier.
Here's to your health.