All the 3.5e-4e books are crazy expensive. I am sure they were printed less, but you can get a nice
S1 mono for the cost of many 3.5 books.
All the Forgotten Realms books, NeverWinter etc are all more expensive than the
2e or even the first editions of Blackmoor, Eldritch, Greyhawk etc.
** expired/removed eBay auction **I assume this is folks collecting chronologically back in time as most players and collectors walking the Earth didnt actually play 40-50 years ago.
Any better ideas or thoughts would be interesting.

I am curious.