Last year my son was a "Hot Red Chili Pepper" for Halloween. I found the costume at a 2nd hand children's store for $4. Great money saving tip! $4 vs. $15 for a costume they'll use once or twice!
This year he'll be a dinosaur! I made the costume from some pajamas and some felt I already had on hand. I also already had a green ear muff hat so I just sewed some triangles and stuffed them onto the pajamas and hat and tail (that I also stiched) and voila! Easy, cheap and so cute! I used light stitches so I can take them out when he's done and he can still use the hat and pajamas all winter! The greens don't match perfectly, but they are good enough for 1 night costume anyway!