This paper analyses the role of agro-systems preservation on making food choices. It employs the “Calibrate Auction-Conjoint Valuation method” (CACM), which relates hypothetical conjoint valuation of product attributes with real market behavior using real economic incentives. The paper also allows comparing the hypothetical and nonhypothetical valuations in order to value the difference between the theoretic and the incentive-compatible WTP for a same respondent and within a single experiment. Thus the paper aims at testing for: 1) the internal consistency on people’s behavior towards sustainable agriculture, and 2) the relevance of the price attribute versus agro-ecosystems preservation for a fresh product. Results suggest that Spanish respondents’ valuation of an agricultural product highly depends on the type of system used for its production. Nevertheless, respondents mainly differ between sustainable and non sustainable production, and do not discriminate between organic and integrated systems. In addition, both the price and the protection of the environment are the most important elements taken into account when purchasing. Moreover, consumers tend to overestimate their WTP in hypothetical settings (60% of the sample). Finally, factors such as gender, respondents’ knowledge towards organic production and practices, health concerns, trust on organic marketing agents and risk perception are significant on explaining differences between individual’s hypothetical and non-hypothetical experiments.