The winning bids have exceeded $2 million in four of the past six years, and in 2012 the auction winner paid $3,456,789.
The top bid Tuesday morning was $370,100.
Buffett is chairman and CEO of Berkshire Hathaway, and the 83-year-old is a prominent philanthropist.
The auction benefits the Glide Foundation, which provides social services to the poor and homeless in San Francisco.
Bidding continues until 9:30 p.m. CDT Friday.
The winner can invite up to seven friends to the lunch. The only topic off limits is what Buffett might invest in next.