YO CHEAPER ON THEIR WEBSITE: https://www.neology.com.au/seagate/exos/ s/o @Tollery. And free shipping
EDIT seller jacked the price for the 20TB AND 16TB. 18TB is the one I got, and is unjacked.**
Seagate EXOS X18 18TB ST18000NM000J SATA CMR 3.5" Enterprise HDD OEM $449.95
Seagate EXOS X18 16TB ST16000NM000J 3.5" 4Kn ENTERPRISE CMR HARD DRIVE OEM $409.95, I saw this one recently which is X16 and ~$300AUD shipped from HK. I don't know the difference between X16 and X18, and whether it worth paying $100 extra for an X18 from an Aussie seller.
JW is cheapest at $949 for the 20TB Exos with AU stock and 5 year warranty.
Western Digital Ultrastar DC HC550 18TB WUH721818ALE6L4 3.5" SATA SE CMR OEM $539.95 - 9 available
Seagate Ironwolf Pro 20TB ST20000NE000 SATA CMR 3.5" NAS HDD OEM $499.95 - 6 available
I think I should get the Exos 18TB X18 and add something over $30.05 to get $50 off with PWESNS, or just yolo 2x 20TB Exos for $1099.90, or get WD because Seagate no good. I'll wait for the experts to fight it out in the comments before I decide.
Decent price, but still waiting for another $329 for 20TB deal D: