(PD) - Dan Kosta and Michael Browne have created a classic cult pinot and a multi-million dollar brand from modest beginnings. In 1997, they started the company by pooling tips they earned as sommeliers. In April, a 10-case lot of their pinot noir raised a record $46,000 at a fundraising auction, or $383 a bottle.

Kosta Browne’s pinot will again be on the auction block this week as the company joins about 170 wineries that have contributed wine and other items for Sunday’s Sonoma Harvest Wine Auction at Chateau St. Jean in Kenwood, which caps Sonoma Wine Country Weekend.

Co-vintners Kosta, 44, and Browne, 48, credit the success of their boutique winery in Sebastopol’s Barlow on their commitment to relentless experimentation.

“Don’t be afraid to say, ‘I don’t know,’ ” said Kosta. “We realize it might take five consecutive lifetimes to learn how to make wine, and you still won’t know everything. When you’re not afraid to say ‘I don’t know,’ that’s when the fun begins and the magic happens.”

In 2009, for example, they sold a majority stake in their company to Vincraft, a private equity group, for an estimated $40 million. In 2015, J.W. Childs Associates of Boston purchased the controlling stake in the winery from Vincraft for an undisclosed amount.