Charity auction of a private lunch with billionaire investor Warren Buffett entered its final hours. The high bid on the eBay auction Friday morning was $775,100, but the biggest bids often aren't made until just before the end, which was scheduled for 9:30 p.m. CDT.

All proceeds go to the Glide Foundation, which helps the poor and homeless in San Francisco. Buffett has raised nearly $15 million for Glide with these auctions over the years. Buffett said he will spend several hours discussing whatever the winner wants to talk about, except that Berkshire Hathaway's chairman and CEO won't talk about potential investments.

Last year's Buffett lunch was the most-expensive charity item ever sold on eBay. The most expensive item ever sold on eBay was a jet that drew $4.9 million in 2001.