This has been covered quite a bit here.
I actually met that guy in person recently, he bought a horn from me. I asked him about this horn and he said that he basically keeps all of his horns on ebay at all times and proces the ones he wants to keep way high. He said the $150K starting price was more just to draw attention to his other horns. Sounds like it worked because he got 20,000 views in the first couple of days and a lot of his more reasonably priced stuff sold.