Since I was required to make a doctors appointment in order to buy parts for my CPAP machine, and since such an appointment was probably going to cost me about $200, I decided to buy my CPAP parts on line.  But just out of curiosity, I asked how much they charged for a new air hose.  They told me $45. When I told them that I could buy that very air hose from Amazon with out a prescription for $8.99 plus shipping, they were shocked.  And since the doctors office seemed to be marking everything up by 500 %, I figured that the $15 face mask on Amazon would cost $75 at the doctors office.  So Amazon cost including shipping $30.  Doctors office cost including doctors appointment, $320.  Caveat Emptor.  No wonder insurance rates are so high.