I was in the same situation as you, looking at ~$2,500 for a new machine here in Sydney.
I managed to get a brand new AirSense Autoset from the States landed here for less than AU$1,000. Including shipping and currency conversion. There are options out there, but mine wasn't obtained on this forum so can't give you links here sorry.
The US machines won't have the ability to connect to MyAir or ResMed's servers as the modem is CDMA for the US and GSM for us here. Warranty and servicing is also another issue, but I was happy to take the gamble on that considering the huge saving on the price.
Another option possibly worth looking at is Gumtree. Similar to Craigslist which the Americans refer to. I have seen a few newish machines listed on there at a fairly discounted price.
OMMOHY, a Holden is Australia's own car. A subsidiary of General Motors. Your current model Chevrolet SS is actually a Holden Commodore built here in Aus.