WD Blue 1TB 7200 at Newegg ... $49.99
https://www.newegg.com/Product/Product.aspx?Item=N82E16822236339
 
But it does seem that WD has shifted the 7200rpm lineup to the Black label for the 2TB and up capacity.
 
Maybe it does have something to do with the latest drive geometry.  Probably worth doing some investigating.
 
Maybe 5400rpm is fast enough for a HDD these days???  Or maybe SSD drives are eating the budget market segment for fast HDDs???
 

Ssd is faster, silent and less heat produced. So a far quieter system. In an ideal world I would have all ssd drives and run Windows from nv add. Maybe a 5400 rpm with ssd cache support might work.....hybrid drive.