I WISH I had a spare room dedicated to just putting cosplay stuff in! SOMEDAY.
I just keep my cosplays in my closet, and props and whatnot just sit around my room. It's funny because you'll walk into my room and see a prop shovel leaning against the wall, my Sweeney and Hit-Girl wig sitting on the floor, ect. Can't imagine what it looks like to someone who's not into cosplay. :B
Or if you're a Depp fan you can look around my room going, "Oh, there's Shooter's shovel and hat, Mort Rainey's glasses, Duke's glasses, and Sweeney's razor. I love it.