I buy the white cardboard ammo boxes with styrofoam trays from Midway. There's several sizes, and each size will hold a wide variety of calibers. I get the case of 100, that's a lot of boxes, and I reuse them. Don't recall ever wearing one out, and I still have a large stash of new, never used ones.
I also use removable Avery labels to label them, I made up templates for the caliber, bullet type, powder, and charge weight. I then print a few sheets up and when I make some loads, I write in the bullet/powder/charge info with a fine Sharpie. I could make sheets with the load data already printed, but then I'd have a full sheet for only one load. Leaving that blank and writing it in works better for me. With the removable labels, I just peel the label off an empty box and slap on a new one, or just duplicate the load on the old label.
These boxes are a little bigger than factory boxes, but the versatility of "one size fits many" appeals to me. I then store the full boxes in USGI ammo cans. I find the SAW cans, or "fat 50's", to be much better, they'll hold more, but they're harder to find. Also have lots of the standard .30 and .50 cans, and a couple of the 20mm. But the bigger the cans, the heavier they are when stuffed full. Not the greatest things to haul on range trips, but excellent for long term bulk storage.
I keep it all on some steel shelving in the garage, but am planning on replacing that with some homebuilt wooden shelves that will be deeper, wider and taller, with lots more usable space. I'll eliminate a lot of the ammo cans and just stack boxed ammo on the shelves. Then it'll be easier to select what I want to go shooting with. Just grab a couple of each instead of several ammo cans with way too much.
These have the bullet and powder printed, just imagine those fields blank....
Ammo Cans 'R Us. There's some of the SAW or "fat 50" cans on the top shelf, compare to the regular .50's.