In my opinion (and I don't want to sound like a conspiracy theorist as much as possible but it's just so preposterously cheap for me) these journals are hiding something from us, perhaps keeping the fact that Data could go for even more expensive in the market, after all, from a single behavioral data set a company could make millions with it already. Plus we have companies who advertise services where "you can monetize your own data", how does that go for in the grand scheme of things?
However even personal data is worth really cheap, that's not mean our personal data is cheap too, if someone never share his personal data to any site, their personal data worth unlimited.