1. What is the correct price? Amazon is doing this to better discriminate customers on offerings, price and quality. It's essentially the sophisticated version of what econ 101 calls "siphoning off the consumer surplus by price discrimination". At this stage, it is highly doubtful that the fixed 10 bucks actually represents the true value that the consumer's data.
2. Externalities. Especially considering that amazon can classify you by other means, people that are like you getting these 10 bucks means that amazon increases its discriminatory power toward you - whether you have gotten the money or not. This is a negative externality - one that the market simply can not solve because we fundamentally lack information and this behavior essentially induces a prisoners dilemma among consumers. Amazon is going to know everything anyway, so I might as well take the 10 bucks.