You have a greater tool - your PC - that can be helpful to get the printouts of diverse colorful sheets. Guide the children, exclusively during the holidays to add illustrations to the colorful-page, and showcase them around the prominent places of the house. This will give them, a sense of pride and joy for their creativity, and would lead to further productive pursuits. Thus, you will witness that there are massive advantages of coloring-page relatively to coloring books. Coloring sheet are economical, costing you only a couple of cents in ink and paper rather than a few dollars for a coloring book.
After watching how mesmerized she was while filling in the images with her newly sharpened pencils, I decided I wanted to color as well. Although the images I colored werent exactly inspirational to me, I enjoyed the experience overall. The next day, I decided I wanted to get my own coloring book with a new set of colored pens. I bought a book full of pictures of mandalas (a circle with complex designs in it). The designs were beautiful and I could imagine them once I filled them with color.