Customizable coloring/other supplies that can be imprinted with your library logo! https://www.4imprint.com/
When we began printing coloring pages, we put out office supplies, and crayons/markers that we purchased ourselves inexpensively.
Later, due to increased usage of coloring materials we were able to secure funding for customized materials for our events.
It's important to search for materials that have no copyright restrictions if you are looking for the fastest way to find coloring pages to use. You can do this by searching for coloring pages in Google, clicking on Images, then clicking More Tools which will then display options for searching by Usage Rights.
However, with varying degrees of copyright restrictions you may be able to use coloring pages if you cite the creator/website if they are labeled for reuse or for noncommerical use.
You can make your own coloring pages with Photoshop! Convert an image to black & white and use the Photocopy Filter to create a coloring page.