That's an utter shame. The guy should have gotten way, way, way more for it than that. I feel bad for him. Frankly, it was stupid to do it through ebay. Just getting word around that he was selling would have likely attracted much more serious offers in the long run. Still, I'm guessing he's not entirely hurting for money in general if he had built that collection in the first place, and 3m is more than enough to retire on. Hopefully his vision works out and the collection is preserved and distributed properly to museums or wherever else.
My guess is the collection features decidedly too little death metal.