I like that effect and your right... always in the eye of the beholder. I may try doing different coloring books with different effects to see which ones customers like most. I really appreciate your time and thanks for providing this example. If you have time, I'd enjoy seeing the steps you used which I'm sure can be done in PSE.
So would you recommend converting the image to a cartoon style first (as in your example) and then applying desaturation, color dodging and gaussian blurring to change it to a black and white coloring page.