Airport Bookstores Have A 50%-Off Program They Don't Advertise
It sounds a bit click-bait-ier than my usual headlines, but if you enjoy a good book while you travel, I promise this one's worth it. There's no secret or trick here, just a long-standing program that's seriously under-advertised; hundreds of airport bookstores and gift shops will let you buy a book, read it, and return it to any of their locations for a 50% refund.
You've likely never heard of Paradies Lagardére, but you've definitely walked past dozens of their locations in your travels; they operate over 850 bookstores and gift shops in airports throughout North America alone, including the ubiquitous CNBC and Relay brands that seem to exist every fifty feet, at every airport in North America.
The program is simple: buy a book from one of their airport locations, and return it to any other of their locations within six months of purchase, for a 50% refund, providing you've still got your original receipt and the book is in decent condition. Use your receipt as a bookmark, and don't spill your in-flight drink all over the pages, and you should be all set.
If you bring the book back in rough shape, they'll still take it and donate it to a local library, but if it's really beat up you may not receive the refund.
One last note - not all Paradies-owned locations sell books, so you'll want to take a moment to browse their map of locations to help you plan out where to buy and return your next in-flight read!