Large capacity drives are still on our "Not Recommended" List
1. Again, as said above ... the "real world" HD failure rate (not the silly backblaze stuff) shows that the larger capacity drives don't quite have the reliability I'd want when investing in drives of that capacity. These drives are two new to pride any RMA rate data but the 3 and 4 TB WFD Blacks in the 3 TB and 4TB sizes do very poorly with 3-4+ times the failure rate of of average.
2. We see just too much of a benefit from SSHDs and haven't bough a conventional HD in over 5 years.
As such, I'm not in a position to know "where to shop". PCpartpicker has a 10 TB and next smallest is 3 TB
I have seen the 5TB 3.5" model for $110 on newegg and the $2.5" model for $227 ... but at 5400 / 5900 rpm I wouldn't "go there".
A web search finds only "articles" announcing the availability of these drives ... if you read them, they are basically almost word for word identical. A PC component vendor issues a press release and the next day "an article" appears on 623 web sites, all saying the exact same thing.