Here is a link to My Amazon Wish List, Everyone should have one, it helps keep you from getting to many coloring books you don't want, (if there is such a thing). I keep mine updated as well as possible with what I want (there is a separate list for what I have).
What I Want, What I Really Really Want....
This is a link to selected Coloring Books and Supplies on Amazon. I update it and rotate the offerings as I find new things. (It might save you some search time when looking for something new.)
Recommendations available through Amazon
And if you are Buying Coloring books as frequently as me, Amazon Prime is a must. So here is a link for that too.
Amazon Prime so the shipping isn't more than the book.