That's how any profession maintains its price of labor-power: gate-keeping. Doctors do it, professors do it, accountants do it. Professional gate-keeping is most often practiced through state licensing. In the case of university professors, gate-keeping is maintained by peer reviews & "apprenticeship." All cases call for advanced learning, access to which is narrowed by standardized exams & "weed-out courses."
In return for publicly sanctioned monopolies, professionals are supposed to serve "clients," instead of gouging "customers" all they can -- sometimes charging standardized fees, instead of wildly fluctuating prices directly determined by supply & demand; to eschew advertising; to uphold high standards of ethics & competence; and so on. :-)
Yoshie