Cheapest it's ever been according to the three wise camels: https://au.camelcamelcamel.com/Western-Digital-5400-Drive-WD…
Don't forget your cash-back! Shopback, Cashrewards, GoCashback etc.
Edit - Apologies it's appears the cashback from the three companies is the same at 4.5%. Brings the total down to ~$283.
It’s been cheaper on eBay deals (eg computer alliance), $330 x 80% is about $265 or so. A good price still excluding site wide promo
Edit: are you sure the 12% cashback includes electronics? They’re normally capped lower