The cheaper is true, but long before there were APRNs, the military made it possible for medics to go on to become PAs, to save money, and to give them a civilian pathway to work after service----NPs are working in just about every setting in health care --- they are a lot like what GPs once were, there for the basics of their practice, and able to pass on cases that exceed or fall out of the bounds of their area of expertise (as you would expect an MD who is a Psychiatrist to refer you to an internist for GI illnesses, etc.