Update

I've been familiar (through copies circulating around my gaming group) with pretty much every single book that was released by WotC during the 3e and 3.5 era, but there's still plenty of books that I never actually bought myself.

Over the last few months, I took steps to narrow that gap; picking up no fewer than seven books that were on my RPG "to buy" list, including Complete Warrior, Complete Adventurer, Monster Manual III, Monster Manual V, Drow of the Underdark, and Secrets of Sarlona. I guess The Art of Dragon Magazine wasn't really on my "to buy" list, but I got that anyway. A few more entries on the Complete series, the newer psionics book, a few of the environmental books, and one or two other odd books here and there and I can consider myself done with buying 3.5. I'm not being a real strict collector, trying to get literally everything, but there's only a few 3e and 3.5 era books that I probably won't ever want to own. And the only place where I'm really lagging are in the setting specific books.

And anyway, those are all owned by at least someone in my gaming group anyway, so I can still get most of the benefits of owning them by borrowing and reading them at any time without having to actually buy them.

Quite liking Complete Warrior by the way. I had forgotten that, among other things, it offered a pretty good substitution for the ranger and the paladin to make them spell-less. Whoops. I could have specifically encouraged those options for my Demons in the Mist game. Although a paladin would have been certainly out of character considering what the rest of the group ended up as.