I am sure you thought of amazon, but here are some items I use.
Magazine size bags and boards for modules; and Ultra Pro 11" X 14" Toploaders. Yep, its a top loader, like for a pokemon card, but it fits modules and magazines. Sometimes these come damaged, I dont know why.
Golden State Art Pack Acid-Free Crystal Clear Sleeves Storage Bags - for box sets. These protect shrink wrapped box sets nicely.
I use these book stands.
KINGDOM SOLUTIONS | Adjustable Wire Easel 2-Pack 3.75" x 4.75" Display Book, cookware, Electronic, Plate, brochure, Comic, Photo, Frame, Cosmetic, Picture, Stand, Pack of 2
And IKEA bookshelves