Seagate IronWolf 8TB (ST8000VN004) $280.50 Delivered (eBay Plus) / $297 + Delivery (Non-Plus) @ Shallothead eBay
Following on from Cheapaschips2 comment which brought Shallothead's competitive NAS hard drive pricing to my attention, I thought it would be worthwhile to do a similar analysis per model and size to work out bang for buck. Whilst the pricing is good, I do wish they would clearly identify the model numbers of the hard drives being sold which is especially useful for those who want certain series or to meet a promotion requirement (such as the Seagate bonus 500GB SSD deal), and also really hope Shallothead tidies up their eBay listings in the future to make it a little bit easier for me to get the details and share the deal with OzBargain ;)
Best bang for buck in Price per TB would be the Seagate IronWolf 4TB (goes against conventional wisdom that it should get cheaper as it gets larger) however given the most popular size on OzBargain typically is the 8TB model (which also happens to be eligible for the Seagate promotion mentioned above with a confirmed model number), I've named this deal based on that. The WD Reds are not competitive at all in this competition.
Note that whilst eBay Plus users can get the 15% off with free shipping, non-Plus members however will only get the 10% off and will need to add on shipping which varies depending on where you live. For Sydney CBD, this is approx $15 based on my random check but YMMV.
Price per TB Analysis
Where a model has "?" next to it, I had to use the eBay pictures to determine the model number which could be inaccurate/out of date.
I will also call out that there seems to be a second IronWolf 14TB listing at $749 (vs $714 above) which appears identical but just priced higher. I have not included it in the table above but if you're so inclined to pay more, visit https://www.ebay.com.au/itm/Seagate-IronWolf-14TB-3-5-SATA-Internal-NAS-Hard-Drive-HDD-7200RPM-256MB-NEW-/264341492722
Comparison with recent deals
For those interested in comparing to a recent Computer Alliance eBay deal, the pricing appears to be slightly cheaper here due to lower list prices (pre-discount) even though the discount % is less than the usual 20% offered at Computer Alliance (for eBay Plus at least). eg. $280.50 vs. $295.20 for the 8TB IronWolf. That being said, I'm reluctant to post a table comparing them given I couldn't confirm exact models for each drive.
Thanks to ItsBarney01 for pointing out incorrect URL for the 4TB IronWolf. Fixed.