How much do you tip after a $3 million lunch with Warren Buffett?

OMAHA, Neb. — The price of a private lunch with investor Warren Buffett could set a record this year, with bids already surpassing $3 million.

The online auction that raises money for the Glide Foundation‘s work to help the homeless in San Francisco wraps up Friday night at 9:30 p.m. CDT. Bids had climbed past $3.2 million by Friday morning.

The record price that auction winners paid in 2012 and 2016 — $3,456,789 — remains the most expensive charity item ever sold on eBay.

Buffett has raised more than $26 million for the Glide Foundation through these annual auctions over the past 18 years. Bidders continue to pay high prices for the chance to talk with the renowned investor and philanthropist who leads Nebraska-based Berkshire Hathaway, and the event raises a significant part of Glide’s $20 million annual budget.

Buffett supports Glide because of the remarkable work the charity does to help people. His first wife, Susie, introduced him to Glide after she volunteered there.

“Glide really takes people who have hit rock bottom and helps bring them back. They’ve been doing it for decades,” Buffett said.

Glide provides meals, health care, job training, rehabilitation and housing support to the poor and homeless.

Buffett has said he gets asked about a variety of topics during the lunch. The only subject that’s off limits is what Buffett might invest in next.

The winners of the lunch auction typically dine with Buffett at Smith and Wollensky steak house in New York City, which donates at least $10,000 to Glide each year to host the lunch.

Buffett’s company owns more than 90 companies including insurance, furniture, railroad, jewelry, utility and candy businesses. Berkshire Hathaway also has major investments in companies including Coca-Cola Co., Apple, American Express and Wells Fargo & Co.