|Reused firefighter costume + cardboard box = super cute!|
Search your house for parts of costumes. For children, a well stocked dress-up box may be a treasure trove of parts of costumes. There might even be costumes from previous years that could be reused by a different sibling or adapted for use again. Even without a dress-up box, other articles of clothing you already have laying around may give you some opportunities for great costumes without spending a lot, or maybe even any, money. Dance leotards and skirts may be the beginning of a fairy costume, fancy dresses from special occasions may be perfect for a princess or angel. Jeans and flannel shirts could be for a cowboy or miner. Sheets can become togas or ghosts. I saw a news clip about "Occupy Wall Street" being a "hot" costume this year, so you may find some inspiration there, possibly with a 99%-er sign covering most of you, or as one of the corporate "bad guys" in a suit. Old clothes you may have been meaning to get rid of could be easily turned into a zombie costume as well.
|A princess, wearing a dress from her dress-up (originally made by Renaissance Costumes and More by Lady Elizabeth, a friend of mine) and a cowboy, wearing clothes he had, a bandana from the dress-up box, and a foam cowboy hat from a dollar store)|
The next place you'll want to try is second-hand stores. Here you're looking for the same sorts of treasures, but with more opportunity for greater variety. Of course this may be pretty picked over so late in the game, but more stuff may be brought in every day, so there still is a chance. Same thing with Freecycle or Craigslist--you might find treasures, but it is awfully late in the game for finding something fantastic without a fair amount of luck.
Dollar or discount stores may present opportunities to find the crucial missing pieces to make your costume perfect for very little funds. You can probably find makeup, vampire teeth, foam accessories like swords or cowboy hats, fairy wings, and many other finishing touches that make it look like you put a lot more money and/or effort into your costume than you really did.
|An oak tree (felt applied to regular clothes), a Tootsie Roll (fabric, foam, and ribbon glued together), and Tinkerbell (dress up box treasure + discount store accessories)|