"Chalk it up to a lucky confluence of events. Most small dairy farmers cannot keep afloat selling milk to large processors at commodity prices, so those who are trying to survive are looking for alternatives. At the same time there is an increasingly sophisticated public that appreciates the difference between mass-produced dumbed-down food and the handiwork of a small dairy that has learned to produce exceptional butter or yogurt or ice cream by doing it the way it was done before World War II, when there was a creamery in every town."
Besides the high price, I suspect that an unnamed problem is that these farmers are limited by industry-sponsored regulations about what they can put on their labels. For example, they may be raising their cows without artificial hormones, but in some states, they can't use this as a selling point.
Locally in Ann Arbor, Zingerman's Creamery is an example of this movement, though not mentioned in the Times article.