A few times a year I'll buy a 'humble bundle' game pack, its a cheap way to get some good games. This week or month they have a Book Bundle from Lonely Planet. I just bought and haven't looked through it yet, but in the past I've liked the Lonely Planet book series + cook books, and this is a way to get 11 (or more) books for under $10.
Lonely Planet tends to be particularly aimed for adventure travel and the back pack set, providing deeper understanding and opportunities then most tourista travel books aim at.
Here's a link:
https://www.humblebundle.com/morebooks