Have you looked at second hand machines on-line, I think Gumtree is one of the sites there? I picked up a used S9 Autoset for $100 from Craigslist. That was an usually good deal, it still had quite some life left on it. There won't be a warranty of course, but seals and tanks are cheap to replace.
There's not a lot, if any, advantage to the DreamStation over the S9. No great leaps in technology, A few pluses, and a few minuses.
As for the old S9, there are no seals to replace. A new dishwashable S9 tank is about $40 online in the US. Not sure in Canada, but there are some online suppliers up there too.
If you get an S9 with the dishwashable tank, boil a big pot of water, turn off the heat, and drop the tank it. Let the water cool, and it will be adequately sanitized. The "standard" tank may melt if you do that. Get a new hose and mask, although many masks will survive the hot water dunk. There's also "Control III" disinfectant you can buy online. READ THE DIRECTIONS. Control III concentrate is nasty, but pretty benign once properly diluted.
Not saying the DreamStation is bad, but it's not clearly superior to the S9. I find the ResMeds seem to be a little more "gentle" on the breathing.
Be careful about what you buy. The medical mafia will screw you and may only be willing to sign off if you buy the machine from the "approved" medical supplier and have them read the data. Be careful that the doctor will approve your license if you have a machine bought from a "third party."
Get the free SleepyHead software here
for information on the main alternative to CPAP.
If it's midnight and a DME tells you it's dark outside, go and check it yourself.
Good point about the specialist archangle.... mine has been far from helpful in the aspect of getting me quickly cleared to drive, he has put hurdles in the way at every turn - which may be part of the reason I have now lost the opportunity to return to my original driving job, and am now unemployed as of Tuesday just gone.
Given I've already spent quite a bit on medical tests and lawyers in an attempt to get my commercial licence back, it might be prudent for me to pay out for the new machine rather than risk yet more obstacles from him.