As for the Dragons of Autumn and Dragons of Winter 3.5 books, I was fortunate enough to find someone who was selling them off at a very reasonable price. (Not nearly what I found the Dragons of Spring book for, but also nowhere near what others are asking for them on Amazon and eBay.)
Something I think I'm going to start doing is actually using the digital copies that I have to keep notes on. This is easy to do, and I don't mark-up... thus devaluing... my physical copies. Never done this before, but I need to roll with the technological advances at my fingertips.
So far, I have plans for the following campaign settings:
- Forgotten Realms
- Dragonlance
- Greyhawk
- Ravenloft
I'm very on-the-fence about Eberron. From what I remember of the setting, it's good but I don't know that there were any "epic" adventures for it.
Dark Sun is basically out. As I mentioned above, I never really played it so I am very unfamiliar with the setting. Same can be said for Spelljammers. I don't even think they made a 3.5 version of SJ, so that works to my advantage.
Though I'm familiar with the Oriental Adventures setting for D&D 3.0, I don't think I'm going to offer it as an option because another DM is working on an oriental themed game as a continuation of the campaign he's been running for several years now.
I posted a poll on a Facebook group for local gamers that I help support, and it seems like the majority prefer Forgotten Realms. Even though my purchasing has been focused on Dragonlance, I think I should turn my attention to FR now and see what I can put together.