The situation where there is just one buyer but many sellers is called Monopsony. This is actually a case that may exist in perfectly competitive markets; it is a subset of perfect competition. The monopsonist has high bargaining power and can dictate the terms of the industry because of this power. Monopsonist has control over the quantity. It is hard to find perfect monopsonies in the market but some examples include that of nurses and hospitals, teachers and schools and athletes and clubs.