Astrid Buffett was heard at "summer camp for billionaires" complaining about $4 coffee, the New York Post reports. US coffee shops charge an average of nearly $5 per cup of coffee, according to a previous Insider report. Astrid's husband, Warren Buffett, is known to be frugal. At the so-called "summer camp for billionaires," 77-year-old Astrid Buffett was heard complaining about having to pay $4 for a cup of coffee, the Post said. Warren Buffett and his second wife, Astrid, have been married since 2006.

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Persons: Astrid Buffett, Warren Buffett, Buffett's, Berkshire Hathaway, Bill Gates, Buffett, Astrid, Astrid Menks, Warren Organizations: New York Post, Allen, Berkshire, Oracle, Post, NPD Group, US Bureau of Labor Statistics Locations: Sun Valley , Idaho, griping, Omaha, Sun Valley, Sun