Seagate Terascale HDD 4TB (ST4000NC001) $120.29 + Delivery ($0 with Prime) @ Amazon US via Amazon AU
Been scouting out for some 4TB NAS drives since I'm a bit iffy about using shucked green drives.
Found these Seagate Terascale 4TB drives on Amazon for a decent price, a bit cheaper than the Ironwolf 4TB drives on sale at least.
From what I could find, there's no direct warranty from Seagate, but there is 3 year warranty through Amazon.
Don't forget your 3.5% cash back through Shopback which brings it down to $116.07.