jolie_amethyst
Would be interested to hear peoples thoughts on storing decks together vs. storing them alone as well.
Can't see that there's an issue with having all or most in one place for storage...it's not like they're going to argue or contaminate one another somehow. If they were, some of the folks here with very large collections might be in trouble!
For my own storage setup, decks I'm currently using most often are snugly bagged and stored together in a leather basket for convenience. That's stored on the same small shelf where I store all the Tarot books, so it's easy to reach. The rest of the cards are in a small drawer underneath that shelf. Depending on where you live, many craft & home decor stores have pretty "treasure chest" type boxes in various sizes at decent prices that work nicely for storing multiple decks. Other people have found that secondhand shops (also known as charity or thrift shops) can be great sources of wood or metal boxes. Vintage luggage (especially smaller pieces like train cases or hat boxes) might also be a good option.
Personally, I just repurposed what I already had: cleared a shelf & emptied a drawer (both already in my bedroom) for them, and dug out a basket from my stash that was the right size...it holds around 8 decks. Nothing mystical or fancy about any of it...I just take the same reasonable care in storing them as I would for any other good working tools.
I do try to match bag fabrics to the right decks though.