Cut out a bunch of coloured circles, put them on black clothes,and paint two large dots on your cheeks. You could be a twister board! :P There's lots of ideas you can chose from, you just have to look sweetie.
v You're lucky you went all the way up to sixth grade. I've never been allowed to celebrate Halloween because of my religious fanatic hypocrite mother. :/
You can make stuff out of your clothes. There are a lot of costumes that you can make simply by mixing and matching clothes, and making things. I'd rather do that than spend like forty bucks for a nice costume anyway.