Not even halfway through June and I've already spent more than I spent in the first five months of the year! But the two books I've bought still bring me to only about $25 on the year, so I'm not concerned* yet. As long as it doesn't become a habit.
*The real cause for concern is that one of the books was because the sale price created the want. It's exactly my kind of thing, but that needs to be a very rare occurrence. The other book was a wishlist book on sale, so totally justified.