Actually used hard disks have gotten pretty popular in the past few years, with sellers like ServerPartDeals building up a reputation by selling drives that are properly tested and recertified. As long as you have redundancy and backups by all accounts they hold up pretty well.
SPD is out of stock as well for all their high capacity, manufacturer recertified drives.
Got the 20TB Seagate recert in May 2025 for $239. Now it's $500 and out of stock [1].
Got another 28TB Seagate recert in Sep 2025 for $398. Now it's $482 and out of stock [2]. Same drive, but seller refurbished is also OOS, but at $700.
I sure hope everything in my homelab NAS outlives the AI bubble. Otherwise, I'll have to shut it down, as getting a replacement for ANY part inside it is going to be stupid expensive. I'm at least thankful I went for DDR4 motherboard instead of DDR5.
Yeah AI killed that market just like everything else. I'm sure the supply of used drives has also dried up as the equation of "cost per TB of power and rack space" vs "cost per TB of replacing with newer, denser drives" has gone haywire.