Honestly? My friends'.
I don't own any paint of my own yet.
We did find out that you can use food coloring (mixed with water, applied with brushes or an airbrush gun) to stain your skin. It stays for a few days, it doesn't smear or rub off on stuff, and it's cheaper than paint. It's hard as hell to work with, though.
I'll upload a photo or two of what we did with it.