At least in Uruguay, a vote costs about US$2,000. This is according to a new paper that looks at the political economy of conditional cash transfer programs. In 2004 Uruguay implemented a conditional cash transfer program called PANES not unlike Mexico's well-known Progresa program. According to Government Transfers and Political Support:
...PANES beneficiaries were 21 to 28 percentage points more likely than non-beneficiaries to favor the current government (relative to the previous one)...Back-of-the envelope calculations suggest that securing one extra supporter costs the government on the order of US$2,000 per year, or one third of national GDP per capita (though this estimate is an upper bound cost if political impacts persist after the program has ended). This implies that a government seeking to increase its vote share by 1 percentage point would need to increase spending by around 0.9% of total annual government social expenditures. Uruguay has highly developed democratic political institutions for a middle-income country, suggesting that some of the political findings could also be relevant for wealthier countries.
I should be quick to point out, though, that PANES shouldn't be confused with the clientelistic 'buying of votes' - according to the authors, beneficiaries were selected based on transparent criteria, not on who they voted for. For even more on conditional cash transfers, check out the aptly named Conditional Cash Transfers: Reducing Present and Future Poverty. Authors Ariel Fiszbein and Norbert Schady will be launching the book at an event at the World Bank next Tuesday.
(Hat tip: Chris Blattman)