A recent two-day wine auction held by New York City’s Acker Merrall & Condit featured an unusually rich selection of mature Champagnes, including such treasures as the 1961 Dom Pérignon and the 1966 Louis Roederer Cristal. As he hammered down the first lots of vintage bubblies, Acker president John Kapon advised the Champagne aficionados in attendance to reach into their wallets now or face the prospect of having to dig even deeper 12 months down the road.

“I guarantee you all these prices will be significantly higher this time next year,” Kapon said between bids. Sure enough, six bottles of the ’61 Dom promptly sold for $8,000 and eight bottles of the ’66 Cristal fetched $22,000. The market for older Champagnes has lately sprung to life, thanks to the growing interest of an unlikely set of buyers: young American collectors.

It used to be that old Champagnes (generally defined as wines with at least 30 years of age on them) were the domain of crusty old Britons, who preferred their bubblies less effervescent and a little more winey, who savored the telltale aromas of mature Champagnes (mushrooms, coffee, honey, hazelnuts), and who tended to cellar the wines in substantial quantities. Americans, by contrast, liked their Champagnes fresh and sprightly. That is still mainly the case, but in recent years, some young, affluent U.S. oenophiles have become aggressive buyers of ancient Krugs and Dom Pérignons.

Robert Rosania, a 37-year-old principal with New York real estate firm Stellar Management, is one such collector. He grew up in a family that prized good food and wine, but he didn’t discover the pleasures of old Champagne until four years ago. He has been making up for lost time ever since. He is now, according to Kapon, the most aggressive buyer on either side of the Atlantic and has quickly accumulated what is apparently an unrivaled collection of Champagne rarities.

Rosania says he is beginning to face more competition at auctions as other wine buffs learn that top Champagnes can age as well as the very best Burgundies and can drink gloriously even after decades of cellaring. “As people become educated about these wines,” he says, “they drink more of them—and are willing to pay more for them.”

Jeff Zacharia, president of Zachys, a retailer and auction house based in Scarsdale, New York, is seeing “tremendous increased demand” for mature Champagnes as oenophiles in their thirties and forties develop a passion for them. “The younger generation really appreciates the beauty they offer,” he says. He thinks the blossoming interest in aged Champagne also reflects market realities: Spiraling prices for blue-chip Bordeaux and Burgundies are encouraging wine lovers to look to older Champagnes, which still offer excellent relative value, and this, in turn, is encouraging collectors to put more of these wines up for sale.

Price increases may not be limited to older bubblies; some recent vintages are already on the move. Liv-ex, the London fine-wine exchange, maintains a Champagne index comprising a basket of readily available têtes des cuvées, such as Dom Pérignon and Cristal. The index has doubled in value over the past four years. The returns for certain individual wines are no less impressive. According to Liv-ex, the 1990 Cristal is up 130 percent since January 2005, and the 1996 Dom Pérignon has soared 108 percent.

On the back of this escalating demand, the pricing for some newly released Champagnes has turned notably ambitious. Dom Pérignon has just brought out a 1975 “Oenothèque” (the firm keeps stocks of older wines and periodically puts them on the market as so-called Oenothèques) at $1,500 a bottle. Earlier this year, Krug released the 1996 Clos du Mesnil, a single-vineyard, all-chardonnay Champagne, at $800 a pop; it now retails for $1,200. Krug will shortly be debuting its newest wine, an all-pinot noir Champagne called Clos d’Ambonnay, which is set to retail for $3,000 to $3,500 a bottle.

Olivier Krug, the firm’s directeur, says the pricing on the Clos d’Ambonnay is not intended to set a new benchmark for high-end Champagnes. He says that it simply reflects the wine’s rarity (only 250 cases of the inaugural 1995 vintage were produced) and quality. But he concedes that $3,000 for a bottle of Champagne would have been inconceivable a few years ago. “The Champagne market has changed,” he says.

Nonetheless, Krug believes that the very best Champagnes are still bargains compared with the equivalent wines from Burgundy and Bordeaux, such as Romanée-Conti and Petrus. “Are top Champagnes undervalued? I’m not sure I’d say that. But I think they still give good value in the world of fine wine.” True, he's not a dispassionate observer, but the market plainly seems to agree with him.