"First, take the company’s customer base, which has long been considered one of Amazon’s most valuable assets. For the 12 months ended June 30, only about half of the company’s 17 million active customers made purchases, noted Mark Rowen, an analyst at Prudential Securities who has highlighted the issue in past research reports."
Where are Amazon’s customers going? I don’t see any other etailer massively taking business from them. Is it a transfer back to shopping offline, or are people really spending less? The last time AMZN fell from $17 to $12, the stock eventually recovered, but you might want to wait a little bit before trying to go for a rebound (aka the "let it get worse and see if it gets better" tactic, or "I want it oversold"). I might go for a couple of IBM shares instead, if they come near 100.
Reading my blog for investment advice is like playing russian roulette hoping that the powder is wet. Do it at your own risk!