I question the assumption that Amazon was actually getting significant traffic/sales from direct-to-Amazon PPC advertising by Associates. On the Amazon Associate discussion boards, the regulars are all people with web sites. If that's a representative sample, then those using PPC are a distinct minority.
Anyone got any real numbers on this?
(Disclosure of my bias--I am an Amazon Associate with a website, and have never used PPC advertising, whether to my site or Amazon's)
I've sold over $1 million worth of amazon stuff mainly via PPC, so I helped a bit. :)
[edited by: BriGuy20 at 6:51 am (utc) on April 18, 2009]