Might not be the cheapest ever but still a great price for a 5TB 2.5" USB3.0 External Drive during these times while AUD is at historic lows.
Ships from and sold by Amazon AU.
Purchased two as these drives are shuckable and mine are going inside a DIY low-profile NAS I'm building. Currently you are able to shuck only Seagate 2.5" external drives as WD and Toshiba have their SATA to USB circuitry implemented directly on the HDD controller board.
Edit: Price has now gone up to $184.45 from the earlier $167.92
Can I ask what NAS you are building?