In the world of Hunter x Hunter, an official hunter license is one of the most sought-after items in existence. Just seeing the number of participants for the Hunter Exam arc go from almost 300 down to just seven makes it clear how valuable but difficult these licenses are to obtain.
The series also reveals that a hunter license is worth several billion Jenny -- aka, enough to set up themselves and their entire family for a lifetime. Let's try to determine how many new hunters out there are passing the exam so they can sell their license for profit.
There are many benefits that make a license so desirable in Hunter x Hunter. With a hunter license, 95% of public facilities are free to use, 90% of countries with heavy travel restrictions are completely available to traverse, 75% of areas prohibited from the general public are free for hunters to venture into, legal consequences for committing murder are drastically reduced, and exclusive access to Hunter websites with hidden information is granted. That's a long laundry list of features that could very useful to anyone, good or bad. Furthermore, it doesn't matter if the license was stolen or paid for -- all you need is to possess one and you'll have the same level of freedom as a hunter who earned their license through the exam.
The hunter exam takes place annually, meaning there's only one opportunity a year for licenses to reach the public's hands. Additionally, licenses can never be replaced if lost or stolen, so there's no second chance if you're reckless with it. Hunter x Hunter has not given much information about previous exams and the number of passing applicants, but it seems it can be anywhere from a single new hunter to around six or seven.
It's easy to see why anyone would want a hunter license, so exactly how many of these sought-after treasures end up on the black market every year? Statistically, it's stated that one out of every five new hunters loses their license annually, but it's unclear if that includes the card being stolen, the hunter decided to sell it, or if it was just misplaced.
Hunter licenses can go for about several billion Jenny on the black market, likely being worth even more for single, double, and triple Star rated Hunter Cards. For reference, in Hunter x Hunter's economy, a canned soda is about 150 Jenny. In Viz Media's official manga translation, $1 is worth about 134 Jenny. Obtaining and selling just one license would be more than enough to set a person up financially for life.
It's easy to see what makes a hunter license so coveted in Hunter x Hunter's world, and these coveted treasures surely do end up on the black market from time to time. The most likely instance would probably be during the Underground Auction hosted by the mafia community during the Yorknew City arc, since such high-value items go up for auction there. A hunter license has no doubt made a few opportunistic sellers filthy rich at some point. It's also understandable why some may want to sell their license -- a hunter's lifestyle is extremely difficult and dangerous after all.
Still, characters like Gon, Kurapika, and Leorio would never trade their hunter licenses for money. Of the seven new applicants who passed the exam in the anime's first arc, none of them showed any interest in selling their license for profit. Hunter x Hunter drives home the point that Hunters always want something more, and what these three desire can't be obtained with all the Jenny in the world.