Moreover, even if we make the heroic assumption that the costs and benefits can be evaluated rationally, we still face the problem that the “value” of one’s decision is also relative, depending on what others have done. I’ve explored that idea a bit more here:

http://www.concurringopinions.com/archives/2008/02/siva_vaidhyanat.html

As Sunstein and Frank suggested in their work on cost benefit analysis and relative position, given the importance of positional goods in today’s society, people who trade off safety and privacy will likely “outcompete” peers who won’t do so. They will have more money and time, and can thereby purchase better homes, send their children to better schools, afford better health insurance, and generally enjoy a higher standard of living than those who take the monetary and time-wasting sacrifices entailed by demanding greater privacy.

Therefore, I think it’s unhelpful to model privacy as something we should “buy and sell,” or even as something we currently do “trade off” for one or another good or service. As David Grewal notes in his Network Power, most of the decisions we make in a networked society are simultaneously forced and free, and only the most doctrinaire libertarian would grant these tradeoffs the imprimatur of “freedom” because they were not “forced” in the technical sense of that word.