The bookstore at Casa Grande Ruins National Monument is operated by Western National Parks Association. It is a nonprofit cooperation association of the National Park Service. Now headquartered in Tucson, Arizona, the association was originally founded at Casa Grande Ruins in 1938. Donations to the National Park Service thanks to sales at the Western National Parks Association bookstores now exceed $4 million annually.
You can find out more about the Association, and purchase many items on-line by visiting the official Western National Parks Association website.
Books about Casa Grande Ruins National Monument of particular interest might include:
The bookstore has much more than mere books! Mata Ortiz pottery (the Casas Grande area is a "sister park" and was likely a trade partner of the Ancestral Sonoran Desert People), Native American style flutes, and Tohono O'odham baskets and pottery are some of the special extras sold.
There are t-shirts, magnets, keyrings, postcards, videos, stuffed animals, puzzles, board games, cactus candy, and tepary beans to name just a few other treasures. All the sales items are related to the park story and all are sold without sales tax since the bookstore is non-profit. The selection changes constantly, visit often!