The cheese was for sale Saturday at Wisconsin Cheese Mart, the Milwaukee Journal Sentinel reported.
The rare, super-aged cheddar, ranging in age from 20 to 40 years old, was discovered this spring at Zahn Cheese in Oconto as founder Ed Zahn, 73, prepared to retire.
"It's good," Zahn said as he tested a 28-year-old cheddar.
"If there's too much acidity, it can sour and go bitter," Zahn said. "And aging's not going to help it any."
The cheese sold from $60 to $96 a pound.
Cheese Mart owner Ken McNulty called the quality of the Zahn's cheddar after all these years a testament to the cheese maker's skill and the superior milk he used.
"It's really acidic, really powerful," said McNulty. "It's definitely an extreme food."