Has no one mentioned shucking yet?

Buy western digital external drives (MyBook and Passports) to tear them apart for the white-label drives on the inside. No warranties after you start using them but they’re essentially the same drive as the red label NAS drives for about half the price.

All storage prices are insane in the current market but if you’re careful and test the drives before you use them (so you can use the warranty if you need to) then you shouldn’t have a problem. Just be aware you’re either going to need to use the “kapton tape trick” or buy “SAS drive adapters” from your online store of choice for about $10 apiece to allow the drives to power on outside of the enclosure.