I'm pretty sure you have to add an extra $5 for an extra colouring book.
Just to note that:
If we do hit the super sized mark and your total pledge INCLUDING SHIPPING is more than $250, you get the extra colouring book anyway. I had actually messaged Rich about this before as I wanted to get an art print as well, he helped to clarify that it is the TOTAL amount pledged that qualifies you for any bonus rewards e.g free art print, extra stickers etc.Every pledge that goes over the $125 mark (including any shipping surcharge) will get TWO sheets of stickers and TWO notepads, while every pledge that goes over the $250 mark (again, including shipping surcharge) will get TWO coloring books for no additional charge (and can still add a third one for $5).