Incentive strategies are used in collaborative user-centric networks, the functioning of which depends on the willingness of users to cooperate. Classical mechanisms stimulating cooperation are based on trust, which allows to set up a reputation infrastructure quantifying the subjective reliance on the expected behavior of users, and on virtual currency, which allows to monetize the effect of prosocial behaviors. In this paper, we emphasize that a successful combination of social and economic strategies should take into account the privacy of users. To this aim, we discuss the theoretical and practical issues of two alternative tradeoff models that, depending on the way in which privacy is disclosed, reveal the relation existing among trust, privacy, and cost.