Grant Golesh, the colorist of 100 Bullets has lots of color guides from 100 Bullets for sale at $15 a pop.
To quote the dealer selling them: While these are technically termed "color guides" for lack of better terminology, they are fully painted pieces, and not simply sections of color painted on acetate like many traditional guides. All of the 100 Bullets guides are on pieces of 8 1/2 X 11 bristol watercolor boards.
He's not wrong. I bought one, and it's beautiful. At $15 a pop these are a bargain.
Here's a link: http://www.splashpageart.com/ArtistGalleryRoom.asp?ArtistId=103