With that kind of money I'd look at Patagonia as well. There's a cheap Aldi and Macpac ones listed on ozbargain right now. My complaint about mine (macpac) is that it's kind of short, I'd prefer a warm jacket that at least covers my bum / overlaps with my pants.
I've seen a few of these things around, they're a bit overkill for our mild winter in Perth. I had no idea they were so expensive, though! My youngest wants one - because fashion. I was looking at the Anaconda range, They were in the $60-$100 ballpark (for kids jackets - not sure if adults are the same).
I haven't tried them, but Huffer are having a 50% off sale on their puffer jackets right now and I'm eyeing it off. I've heard a few people rave. They're around $500 full price, so a sale is worthwhile.