Good prices for some high capacity WD RED Pro drives using CMR tech.
Western Digital RED PRO 14TB Model WD141KFGX
Prime Exclusive Deal, Ships internationally
Western Digital Red Pro 20TB Model WD201KFGX
Prime Exclusive Deal Ships internationally
Local prices for the 14TB is around $640 and about $900 for the 20TB.
Purchasing 2 will give you a further 6% discount, however this could attract customs duty if your purchase exceeds $1000 AUD.
If you do not mind "shucking" an external hard drive to harvest a bare drive and voiding it's warranty, there's also a Western Digital 18TB Elements Desktop for $409 from Amazon UK or a 20TB one for $486.20.
the 18TB WD Elements will most likely have a WD180EDGZ (White-label CMR drive), according to Ozbargainer's comments. I'm not certain what drives will be used in the 20TB SKU.
Note SMR isn't ideal for RAID, and is more suitable for cold storage applications.
is this ok to put into desktop PC that is turned on and off each day?