Monopsony

In economics, a monopsony (from Ancient Greek μόνος (monos) "single" + ὀψωνία (opsōnia) "purchase") is a market form in which only one buyer faces many sellers. It is an example of imperfect competition, similar to a monopoly, in which only one seller faces many buyers. As the only purchaser of a good or service, the "monopsonist" may dictate terms to its suppliers in the same manner that a monopolist controls the market for its buyers.

http://en.wikipedia.org/wiki/Monopsony

The Internet as Playground and Factory - Ulises Ali Mejias from Voices from The Internet as Play on Vimeo.