With Halloween coming up, what are some clever, frugal costume ideas?

For example: last year, I went as a "crazy cat lady", so the costume consisted of an old, fuzzy robe, fuzzy pj pants, a bright pink and stained tank top, slippers, and I actually put a little bit of lotion in my hair to give it "texture", then messed it up and hair sprayed it in place. Then, I took some of the dozens of cat plushies that I own, and pinned them to my robe so it looked like they were climbing on me.