Would you consider that him trying to buy you or would you think of it like him taking you to the movies and paying for it? What are your thoughts on a book date? Take into account that she is the book worm not me.
You have a good thought there, but it would be weird to get a gift on a first date. I think you should try to go when the store has an event like an author appearance. A big bookstore usually will have events like that pretty often. That will give more substance to your date, because otherwise there's only so much time you can spend at a bookstore.