This, for example: "We do, however find some price variations for Kindle ebooks on www.amazon.com, depending on if the user is logged in to the site or not." [h

This, for example: "We do, however find some price variations for Kindle ebooks on www.amazon.com, depending on if the user is logged in to the site or not." [http://arxiv.org/abs/1307.4531 http://arxiv.org/abs/1307.4531] Also see Figure 1 for the evidence of prices highly varying over time. It implies that different users pay different prices within small periods of time.