I think the free machines are only free for fixed pressure?
I’ve been using Respironics and PhillipsRespironics for 12 years. Only recently bought a Dreamstation Auto from Secondwind Cpap in the US. That was before we got landed with the GST for stuff under $1000. It cost me about $750 AU whereas the Au price is well in excess of that, more than double.
When you are on a Mac, as I am, you also need to consider whether you want to access your machine’s data. I bought the dreamstation for only one reason, that being that my older machine didnt use a data card that I had a reader for, and even if I did, the software was PC only. It didnt bother me for a long time but eventually I decided I wanted to be able to see what was going on… and the Dreamstation talks to an app on my phone. And its information is pretty much useless. So I use a software called Sleepyhead (written by an Aussie guy) and its been illuminating. Its also been handy to be able to print out a summary for my GP ahead of the annual medical for Driving. Sleepyhead is also compatible with the REsmed S9 and S10. https://sleepyhead.jedimark.net. The beauty of this software is that once you learn what all the graphs are about, you can see what you need to do to improve your outcomes.
I like really lightweight masks, for years I used the REspironics Comfort Classic, but had to find something else when it went out of production… currently I vary between a Phillips Pico and a BMC nasal mask, the designation of which I forget. Bought both on ebay, since both came with all three sizes so one was bound to fit well, and they did, indeed. I think I saved about $200 doing it that way.
Overall my machines have assisted me a lot, my AHI is down from 44 to 2-3 per hour and sometimes I have NO obstructions at all during sleep… The reason it stays at 2-3 or whatever, is the dreaded hypopnea which I have had all my life.
I’m rambling and thats because its 3am and I didnt get to sleep til 11, and awake again at 1. There are non-OSA reasons for me to be awake, and I’ll go back to bed again shortly 
