concierge medicine
http://www.kiplinger.com/article/spending/T027-C000-S002-6-things-to-know-about-concierge-medicine.html
I have read about the concierge doctors.
The doctor I read about had his practice in a lower middle class area. His patients appeared to be a good cross section of the population.
Definitely not the wealthy.
Before I retired a group was trying to set up a cash only system of doctors at truck stops for truck drivers. One or two states blocked it because they would not take insurance. Government = no common sense.