Free pick-up from warehouse in Alexandria, NSW.
This is a good price for a top-quality ergonomic chair - I bought mine earlier on sale but at $750. Extremely comfortable and comes with the Herman Miller 12-year warranty. Probably not for everyone, but as someone who sits at my desk for long periods, saving me from back pain is well worth the $60/year.
I've noticed a previous deal from January 2014 for $490 - back in the heady days of the high AUD, but I have not seen anything near as cheap recently.
They are indeed very comfortable. Bought two at that 2014 price and even then thought long and hard if it was worth it.
Armrest height adjustment a bit hit and miss, and chair could be hard to clean if it's dusty. If I bought them in 2014, still have 10 years warranty!