I like making costumes. You get to show your creativity and it usually doesn't cost near as much as buying or renting one. I've been a bag of jelly beans, a spider (8 legs and all), 1940's gal dressed to the 9's, and more.
Kids look so cute when they don't have a massed produced outfit. It's safer too if you don't use a mask and just paint their faces. They're better able to see. There were a couple of gals who used to have a website...the side tracked sisters? I think that was their name, and they had alot of cheap, creative ideas on how to make costumes for kids. Might be possible to look it all up on the net.
CJ