Closing CPC Price Gap or Irrational CPC Buying

John Battelle wrote a post where he cites a recent Blue Nile earnings statement

I have a client in the diamond industry, and he was ready to jump into the PPC game but pulled out just before. What was his reasoning? He was concerned with PPC fraud. But what was I worried about? I was worried about a dozen other people, like my client, getting into PPC at the same time (i.e. Valentines Day season). All these inexperienced people bidding on expensive keywords, doesn't mesh well with me. I am with Blue Nile's CEO Mark Vadon on this one.