If they raise prices, people will go elsewhere. Walmart, Target, even Sears, they all run on-line stores. Amazon may have strong negotiating power with suppliers, but look at Walmart's negotiating power. Retail history is strewn with the carcasses of behemoths that lost their way trying to corner markets. Look at Joshua Frantas' comment on the original Eugene Wei piece. He has some understanding of the retail business model and makes some good points. In the end, Amazon is a retailer.
I'm also concerned with the opacity of their financial reporting. Yeah, we don't want the competition to know exactly how we do what we do, but apparently their financial reports are impossible to parse.
When the BoD decide they have had enough of Jeff's megalomania and decide to reward the shareholders, that's when we will find out what Amazon's business is really worth.