I got a 4TB WD My Book on Google Express for $67.99 after applying new customer promo code FALLSAVINGS for 20% off. Shipping is free.
From what I have read you can shuck the drive (most likely WD Blue) and reuse the enclosure with a different drive by modifying the board.
Sold by Fry’s. Offer, availability, and tax will vary by location.
https://express.google.