LJC asked about where to find bags of polystyrene beads to make your own bean bags, and in the comments someone linked to Love Sac, which has at least one shop here in Seattle I’ve seen. We have had something similar to the 5′ round for a few years, we call it the poof. (I bought it online from a place which has since disappeared.) I’m not entirely sure about the LoveSac, but ours is filled with chopped up foam pieces which don’t make noise the way the polystyrene beads can. I have spotted bags of the foam bits at fabric shops in the area with the foam blocks. I have actually been meaning to re-cover our poof for a while.
Note to self: check out the foam shop in Seattle, they might have larger quantities of chopped foam for sale.