Ummm… I don’t live in the US and $50 is A LOT for me. My monthly salary is about $500. All of these 2TB drives are used and dicomissioned (replaced for larger one, they’re from work). I just don’t have the funds to replace them. The NAS is DIY as well.
And drives are not that cheap around here. They are, but not as cheap as in the US. SSDs are about the same price though… but our salaries are not.