It seems WAY too good to be true. If you look closely, he has pictures of the 400 2.8 on the auction for the 500. He also says he is selling the 500 to fund the purchase of its big brother, the 600. Yet he has a 600 up for sale too.
In this case, I wonder if it's someone who's getting out of the headlight business and is going to sacrifice their ebay name/feedback ratings for one big rip-off session. (perhaps making $20K or more in the process) If you're going to quit anyway, why not go all out and make a bunch of extra money?
What else could explain selling off "$100,000" worth of photography gear with all of the auctions ending at exactly the same time?