I think I passed the $1000 mark within the first two years of 3E, given the number of splatbooks, monster manuals, core books, campaign settings, etc., that I'd picked up by then. I hit book buying burnout (BBB) somewhere in Year 3 or 4, I think, and slowed down quite a bit. I would guess that I've spent well over $3000 on 3E/v3.5 alone, and that doesn't include miniatures.
I wouldn't be surprised if my entire collection of RPGs and support material doesn't exceed $10,000, but that's two decades of collecting in four major game lines (D&D (various editions), oWOD, HERO 4th Edition and Traveller (all systems)).
Sadly, though, I think it will soon be time to start letting go of some of this acquired gaming wealth. My wife would prefer that we do some spring cleaning and perhaps get rid of some of those boxes. *sigh*
With Regards,
Flynn