Sometimes making your own costume instead of buying something that is specifically that can save you money.
I once put an entire Patrick Bateman costume together for less than $10. It was interesting walking around a party in just white boxer shorts, running shoes, and a chainsaw (no, it wasnt a real one). People definitely understood it.
Putting your own costume together, in my opinion, is not only cost-saving, but also fun (and easy since you can get pretty much anything on ebay or in stores, nowadays). My last few Haunt costumes for Knott's Scary Farm are actually my own items that I put together.
"NATURAL BORN KILLERS"
1st Place - MiceChat Gumball Rally 2012