Hard decisions time... The black and white (grayscale) version would be pretty cheap but look not as nifty.. The color version would run 30-40 bucks... Given that the first book is currently 72 pages, I don't know whether that sort of expense is justified or not.
Solution: I will just do both. Black and white (grayscale) version and the more deluxe and infinitely better color version.
Sigh.