Imagine buying one for cheap because it has some bad blocks and it’s unreliable to keep real valuable data on it! I have a 8 TB HDD bought for like less than a $100 a decade ago, from a friend though, as he had some bad blocks there. I host only media for the HTPC there, but it’s been a solid all these years. And when it dies, sad, but nothing valuable that I cannot redownload.