I love finding old adventure books from my childhood – but eBay and many online shops often charge top dollar. Here’s some cheap sources for rarer paperbacks.

• https://www.abebooks.com/
• https://www.thriftbooks.com/
• https://www.bookdepository.com/

Or, if you are so inclined, be sure to check out the Internet Archive’s Open Library. It often has the books for free checkout.