I have run a sleep lab for many years and as more people are dealing with high deductibles and excessive copays many people are looking to purchase their own PAP devices rather than go through insurance. This has its good points and it also has some very dangerous bad points. I have seen too many people come through my lab who have done this the wrong way and are now paying the price.
The first thing you need to remember is that PAP is a medical device and as such needs to have a written prescription to get it. That is because it is set to your settings, the settings that are needed to treat your particular sleep apnea. These pressures are not arbitrary, they are either through a study or by the use of auto-titrating devices that are set up to work with you.
If someone is selling their machine that means they are not using it for one of two reasons, it is old and they received a replacement machine or they have chosen not to continue their therapy that it was determined they needed. Remember that sleep apnea can lead to issues such as high blood pressure, heart attack, stroke, colon cancer, and Alzheimer's disease, just to know a few disorders. If they have chosen to discontinue therapy they should not be selling the machine because they may need it again when they have future issues and insurance will not need to replace it.
The machine is not set for you but for the person it is being bought from. It may be the wrong type of machine for you, it may be set at the wrong setting, or the equipment may not have been properly maintained and could cause the new user health problems. Think about it, someone did not clean their humidifier for the six months they used the machine and then they put it in a closet until it was sold. How much could have been growing in that device.
There is no one to set the pressure in the new machine. No DME company is going to set the pressure or replace the supplies or check to see if the device is working properly if they did not sell the device to you. No sleep lab is going to take liability for a machine that was purchased online from another patient.
If you want to purchase a machine yourself after you have your study you need to go through a reputable DME company. There are many out there and they do have the ability to sell used machines that may have been returned to them because someone did not use it. They will also have access to new supplies such as masks, humidifier chambers, hoses and filters. You must have a copy of your sleep study and your prescription in order to purchase a machine. That is due to the fact that it is a medical device, just like you need a prescription to order specific medicines.
It is essential that you look at your PAP as a medical treatment and not just something that your doctor has told you to use. It is one way to improve your overall health and prevent illness. It must be properly cared for and maintained. If you have a device that is not working and it is older than 5 years your insurance company will replace it with a new one as long as you have your studies and current physician noted and prescription. If it is less than 5 years old you need to contact the DME company you obtained the machine from so they can send it back to the manufacturer for repairs. Just remember it is your health that you are caring for and that you should always take your PAP therapy seriously.