Comment by elric
You don't need a prescription for CPAP masks and you don't need a prescription for CPAP devices. You can freely buy both in most parts of the world. If you happen to live somewhere where you can't (and you can't get a prescription for some reason), then I suggest you find an online reseller anyway.
From a few minutes on Google, it appears like most developed countries require a prescription to purchase a CPAP device, including the US (varies per state), Canada, UK, Australia, Germany, France and Italy.
The most notable exceptions I find are Japan and Singapore, where it can be purchased without an Rx.