The price premium for high capacity HDDs is the reduced number of required disks. Hence, less power consumption and simpler hardware to host the HDDs (e.g., 4 slots instead of 6 or 8).

But also increased risk… Its way easier to secure 8* 5TB drives, then 2* 20TB drives.

A 2* 20TB means you need to go Raid 1, where as 8* 5TB drives means you can go 2 Parity and 6 data drives. Aka 30TB usable and 4 times shorter rebuild times. And this also scales to the same effect…

Combine that with something like Unraid, where you do not strip your data over a raid, your chance of a catastrophic loss of all data is WAY less with more smaller drives + parity (and the benefit of more independent filesystems, then one big bulk one. Speaking from experience).

For companies, sure, those guys just make massive arrays with multiple redundancies but for self stores More and smaller is better (in my opinion), what is in major conflict because ironically, the cheapest drives in Germany are in the 14 to 20TB range. And you pay price premiums on the 12 to … 4TB drives.

Interesting how prices different per region. Here in Germany, its mostly 14~20GB drives that are the cheapest, and 12~1TB are not worth buying.

https://geizhals.de/?cat=hde7s&xf=3772_3.5

Ignore the first SAS one, that is one seller on Amazon.

And second hand HDDs are even worse priced on places like ebay. To the point there is little reason to even look at second hand drives. Same applies to a lot of PC hardware, that tends to be more expensive second hand on ebay then brand new from stores.