Miro, 14, was one of the winners of "Grow Your Own Business Challenge," a nationwide contest related to the animated "Secret Millionaires Club," which teaches children about finance and where Buffett voices his own character.
"He's a nice, down-to-earth person," said Miro, who lives in Short Hills, New Jersey. "I entered this competition not really as an entrepreneur because I wasn't experienced in business. But I had an idea. Now business people are giving me advice."
The contest, in its fourth year, attracted entries from more than 4,000 boys and girls ages 7 to 14. The top entrants flew to Omaha, Nebraska to be judged and show Buffett their ideas.
"You're looking at the future and it's a pretty good looking future," Buffett, chairman of Berkshire Hathaway Inc and the world's third-richest person according to Forbes magazine, said in an interview.
Bergen won for "Beyond the Books," a website that lets people work together to create online courses and study guides, in a "Wikipedia of education." People would pay to advertise, or pay a monthly fee to have ads removed.
Bryn Hansen, 11, and Emily Harkins, 12, of Omaha, won the team contest for "Keep Track Sticky Back," sealable plastic pouches costing $7.99 to $66.99 that have sticky backs so they can be attached to nearly anything.
"This competition has taught us a lot, not just business skills but also cost-evaluation, problem-solving skills, and business etiquette, and how to interact with other people," said Emily, who was on "cloud nine" after winning.
Winners each got $5,000, and said they plan to invest it toward their businesses. Bryn and Emily may also seek a patent.
Buffett gave each finalist 10 Class B shares of Berkshire -if they vote to reelect him next year as chairman.
Many entries were pure online concepts. That is a change from when Buffett would buy Coca-Cola six-packs at his grandfather's grocery store for 25 cents, and then sell bottles for a nickel each.
"They've had the benefit of the Internet," Buffett said, "and that's reflective of the products they've come up with. They are leagues ahead of where I was at the same age."
Still, Buffett remains a role model. "He has a ton of inspirational quotes to believe in yourself, to save money, and maybe someday grow up to be someone like him," Bryn said.
The Fairholme Foundation sponsors the contest. By Kids for Kids Co oversees it. Genius Brands International Inc created "Secret Millionaires Club."