There is a gift shop at the Shadows visitor's center, but they don't have any on-line purchasing. I didn't buy anything there, so I can't give you any other information about it. If you see or know of a book that you want, you might try phoning them.
What to buy: They do have other items than books, but I don't remember what they were.
I took this picture because the tattoo parlour was one of the places that were open on Saturday approaching 4 pm. I have been completely unable to find anything about this place or the stained glass place next to it on the internet. So if anyone recognizes it - please let me know.