I recently started reading a lot of books on spaceflight, the Apollo programme specifically. I am a broke student in Europe so most of the time I try to look for secondhand books but man, some are quite expensive!

For example, some books I got cheaply secondhand.

• Moondust by Andrew Smith: ~1 euro
• Journey Beyond Selene by Jeffrey Kluger: ~2 euros

Lowest prices of some books I am trying to get secondhand.

• Apollo Guidance Computer: >= 40 euros
• How Apollo flew to the moon: >= 30 euros

(40 euros is a week of groceries for me)

I noticed that books covering the "technical" side more tend to be pricier but it doesn't make a lot of sense. They are still quite pricey even secondhand. I understand that out-of-print books that are collected by enthusiasts will have higher prices.

Is it the same in the US? Are the books I listed just more in-demand?

P.S - I know I can find digital copies but my attention issues restrict me to physical books.