I really enjoy old, out of print gaming supplements (adventure modules in particular) and few things are as delightful as coming across some old RPG swag in a used bookstore.
Recently I grabbed these for about five bucks each.
Now normally I can justify a purchase with the knowledge that I'm always on the lookout for a fresh adventure setting or interesting plotline (in the sense of unusual setups, unique challenges, or distinctive NPCs who have compelling motivations).
Treasures of Greyhawk fits that bill and has a clever puzzle or two (incidentally the Robin Wood cover art also appeared years before it was used here a a Dragon Magazine cover--my very first issue in fact).
In the case of The Rogues Gallery, however, there isn't even a chance that I'll use the lists of NPC stats.
No, I bought it for the art and to look over the original AD&D characters (at least one version of them) played by Gary, Erol Otus, Rob Kuntz, David Cook and others.
I guess that makes me ... *shudder* ... a collector.
Where does that particular rabbit hole end?