I've bought from #2. They will likely set the machine to CPAP mode to what's written on your Rx.
Of course, you can change modes and set a range. #2 also ships internationally. You could have it shipped to Canada -- unless there's some customs/import duty I don't know about.
INFORMATION ON APNEA BOARD FORUMS OR ON APNEABOARD.COM SHOULD NOT BE CONSIDERED AS MEDICAL ADVICE. ALWAYS SEEK THE ADVICE OF A PHYSICIAN BEFORE SEEKING TREATMENT FOR MEDICAL CONDITIONS, INCLUDING SLEEP APNEA. INFORMATION POSTED ON THE APNEA BOARD WEB SITE AND FORUMS ARE PERSONAL OPINION ONLY AND NOT NECESSARILY A STATEMENT OF FACT.
As others have said, any cpap prescription will work for an auto-cpap prescription for online retailers. Not necessarily so for brick-and-mortar stores. Many posters have reported that their local supplier will only provide what is exactly on the prescription EVEN IF the doc includes a RANGE of pressure settings!
Depending on where you live, you might also find a good selection on Craigslist. It seems that a lot of people get one on insurance, decide they hate it, and sell it on Craigslist. I had no compliance requirements for my insurance (private, through work). Or perhaps they are just getting them to re-sell and make some money. It takes all kinds. Some will ask for the moon in terms of price, but if you keep watching there are reasonable sellers of near new machines. And if you keep watching... I got an S9 Autoset for $100. With 11K hours it was not gently used, but has enough life left it in to serve as a backup machine.