Of course there's room for interpretation what exactly counts as "cheap", for me it's when the price is below 5€, others may have different standards, I guess we'll just have to deal with that. Just recommend whatever you think falls into this category

I'd like to start this thread with two books by Mathieu Ricard available for 4,65$ each:
Mathieu Ricard: The Art of Meditation
imo one of the best introductions to meditation, and
Mathieu Ricard: Happiness: A Guide to Developing Life's Most Important Skill
haven't read this one yet, but since it's by Ricard I have some confidence it's a good read. Afaik both books are not special offers but long-term low priced.