1) pay with personal data
OR
2) pay with an actual monthly fee
Which would you choose?
What would be your upper limit to pay?
Is this for any data service, or would you pay different amounts for Facebook vs Instagram or others?
On a related note, Facebook revenue for 3rd quarter of 2012 was 1.26 Billion [1]. Their total user base is 1.01 Billion [2]. That translates to ~$1.25 quarter/person or ~$0.41 month/person.
Obviously Facebook's value is in huge data sets, i.e. the value of the population is greater than a sum of its parts. Nonetheless, it doesn't seem unreasonable to possibly be able to pay your way to privacy.
[1] http://www.nytimes.com/2012/10/24/technology/facebook-revenue-surpasses-forecasts.html?_r=0
[2] http://finance.yahoo.com/news/number-active-users-facebook-over-years-214600186--finance.html