Most of the people here on the boards don't collect 3.x edition stuff, so you have probably done the most research on the subject.
I collect 3.x edition stuff, but I'm in the minority, it seems.
I'm willing to bet it would sell better to a collector af autographs rather than an
RPG collector (unless D&D goes into a 4th or 5th edition), so don't expect to get more than, or even as much as, you paid for it originally.
Probably not what you wanted to hear - just putting my observations out there.