Ziploc Flexible Totes (XXL) $5.31, Ziploc Big Bag Double Zipper (3-Pack, XXL) $5.41

Flexible, so you can squeeze them under beds, into closets or onto shelves
Use them for bedroom storage, closet organization and more
Unlike rigid containers, they stay folded away until you need them
Made of thick, semi-transparent plastic; Strong enough for everyday use