I put my cards in bags. There are perfect bags at Hobby Lobby that hold a kingdom card. They work well for up to 30 cards, so I use them for Gold and the victory cards, but I bought bigger bags for Copper and Silver. The bigger ones I bought are too large, but they work when I fold them over.
I wouldn't dream of putting them in a bag, though. I would just be worried about gravity taking its toll on the cards if they are stacked awkwardly on top of each other.
But I did start this process off with the intent of using the bags as the randomizer. I think I started this with Prosperity…maybe Seaside. I had enough cards to put into one box and shuffle them around a bit. It even made a pretty handy Black Market deck.
I have too many for shuffling around in a box, so now I have them filed alphabetically. They are still in their baggies, mostly because I haven't been motivated to create dividers for them. Putting up is kind of easy because I don't take the cards out of the bag unless it's been bought. Why bother pulling Workshop out of the bag when Ironworks is out there? Why pull Moat out of the bag when there are no attacks? Why pull Scout out of the bag?
I'm trying to figure out a better way to store my cards, but this rumbling rumor of an official storage device has intrigued me. It'd be so much easier if I can buy one.