Penn State Press is offering a discount for the remainder of this month (so, today and tomorrow) for people purchasing books off their website. Typing in “APR30” will get you 30% off all books on the site, including their Magic in History series.
These books are not discounted on Amazon, so there’s a potential here for some savings. I ordered a paperback just now, and while they do charge for shipping, the overall rates are less than what you find elsewhere. It should be cheaper if you’re ordering hardbacks or multiple items.