There are also related factors to the fitting of the mask to each and every person and the leakage.
You mask should be fitted each and every night in the supine position as this is the normal sleeping position, or is it?
If you fit it in this position, but sleep on your side, your facial tissue re-distributes and completely changes. So if you roll over during the night, the fitted mask may no longer be fitted.
When you are lying in the supine position, the fluids in you tissues no longer are affected by gravity in the same manner to which they are affected when standing. As with any fluid, they tend to settle to the lowest areas over the course of the night. As a result, you facial shape changes somewhat, thus negating the masks adjustment again.
The mask that fits you is no different than a pair of shoes. It needs to fit you, your sleep style and must meet you bed environment. Everything that you do and contact in the bed affects the mask and you.
Make sure you get copies of your complete sleep study and a copy of your script. LET SAY THAT AGAIN - GET COPIES!!!!
There are many sources for CPAP supplies, which are cheaper than your local DME and your access to them, in many cases, require you have your study and script.
In so far as ebay and masks. you have to read the listings. Sellers are very ingenious when it comes to selling a mask. They can list it as parts, but it is still a complete and new mask.