My costume came almost entirely from my closet. I already had brown mary-jane shoes, brown pleated skirt and black rimmed glasses, I bought the knee high socks for a couple bucks at a Halloween store and and orange sweater at a thrift store for$3 or $4…tada! Instant Velma from Scooby Doo!
Here’s some other last minute ideas:
http://www.brit.co/costumes-you-already-own/