I think that it is out outrageous that my doctors office requires a prescription to buy parts for my CPAP machine.  After all, I already own the CPAP machine.  And, it is not like I am endangering myself by introducing some new chemicals into my body.  I am only repairing a machine that they sold to me.  This is like an automobile dealership requiring that all oil changes be performed by the dealership.  I wonder if they would require a prescription to buy parts for a wheel chair?  Well anyway, thankfully there is Amazon!