I completed the SANS Security Essentials course last year and still have the study books.

401.1 Network Essentials
401.2 Defense-in-Depth and Attacks
401.3 Threat Management
401.4 Cryptography and Risk Management
401.5 Windows Security
401.6 Linux Security Essentials

All latest editions (2019) and in immaculate condition. I'm looking to move them on, Fleabay, Rainforest etc - but any ideas on their value?