I picked up some of these hats from the Dollar Tree last week. They came 2 to a pack, in pink and yellow. I decorated them with sharpies and acrylic paint, to (vaguely,) resemble Pikachu and Jigglypuff for my son's upcoming birthday party. Although my drawing is pretty er...simplistic, L thought they were cool, and I like them better than paper hats.
I know Michael's carries similar hats in a wide range of colors, and it occurs to me that you could use the same premise to make Yo Gabba Gabba, Veggie Tales, or Sesame Street hats, or basically any other simple character.