Not the historical lowest.
But if want to buy WH1000XM3 and prefer a brand new headphone and has saved AMEX credit, you can get the WH1000XM3 headphone at Harvey norman.
Link:
Black - https://www.harveynorman.com.au/sony-wh-1000xm3-wireless-noi…
Silver - https://www.harveynorman.com.au/sony-wh-1000xm3-wireless-noi…
How have people gone with negotiating price at Harvey Norman? Success stories/failure learnings?
In theory $370 would be a decent result (assuming no other use for the credit) as $320 is usually the lowest price posted.