As craft beers have become more popular, a black market has emerged. The black market consists of opportunists who sell hundreds of dollars’ worth of top-rated beers that are hard to find, in short supply, or illegal to ship.
For example, a Vermont woman was charged with selling five cases of a popular beer on Craigslist.
These black market sellers are bypassing many legal requirements in selling alcohol, such as acquiring liquor and business licenses, paying applicable taxes, and selling responsibly (e.g., prohibiting sales to minors).
A USA Today article has more on the topic.