"New York City mayor Michael Bloomberg's narrower-than-expected re-election campaign cost the billionaire some $102 million, or about $183 per vote, The New York Times reported on Friday evening, making him the top-spending self-financed politician in U.S. history."

Reuters reports:
Data on the mayoral election released on Friday found Bloomberg's run for a third term in office, which required special legislation overturning a city law that held the mayor to a maximum of two terms, was the most expensive campaign in municipal history, the Times said. Bloomberg, the richest man in a city with no shortage of millionaires, surpassed past campaign expenditures of $85 million in 2005 and $74 million in 2001, the report said.