The price tag for lunch with the investor Warren Buffett? $1.5-million, and counting.

Each year, Mr. Buffett auctions a lunch on eBay and donates the winning bid to the Glide Foundation, a social-service group in San Francisco.

Bidding doesn’t close until 10:30 Eastern time tonight, Friday. But it seems likely that this year’s winning bid could top last year’s — $1.68-million — given the flurry of bidding that typically takes place at the last minute, said Tod Thorpe, associate director of development with Glide.

Winning bids have ranged from $25,000 to 2008′s eye-popping $2.1-million. Mr. Buffett started the auction in 1999.

“People who are followers of the investment strategies of Mr. Buffett are very interested in having time with him and each year that interest increases,” Mr. Thorpe said.

The annual Buffett gift is a significant source of income for the medium-sized charity, which has a budget of about $16-million.