My skeleton costume is very easy and cheap to create. My sister and I went as sister skeletons for Halloween this year. Our costume consisted of a t-shirt, under shirt, leggings and make up/ paint. You can either pick a white t-shirt to cut with black under cloths or the opposite. The way we made our shirt was simply turning the t-shirt inside out and then drawing the outline of the rib-cage of a skeleton and then simply cutting on the lines.
When drawing the outline try not to use a thick marker, or something that will bleed threw your shirt (if using white shirt). In doing this it only took 20 mins to draw and cut the design. After making the shirt, comes hair and make-up. I choose to do a dark smoky eye and then paint a black skeletal facial expression. Then for my hair I just simply teased it so get the scary/drastic look. Then my sister chose to paint her face white and then adds black skeletal fetchers with face paints. She then chose to do a crazy updo/pony tail. My sister got this idea from watching the Martha Stewart show.