the catch is you can just buy an internal for 10$ cheaper.
Data Hoarder
We are digital librarians. Among us are represented the various reasons to keep data -- legal requirements, competitive requirements, uncertainty of permanence of cloud services, distaste for transmitting your data externally (e.g. government or corporate espionage), cultural and familial archivists, internet collapse preppers, and people who do it themselves so they're sure it's done right. Everyone has their reasons for curating the data they have decided to keep (either forever or For A Damn Long Time (tm) ). Along the way we have sought out like-minded individuals to exchange strategies, war stories, and cautionary tales of failures.
This is normal price
As it was mentioned, it's the normal prize now. Just check the prices next time for alternatives or check on a few sellers.
The best $/TB for this form factor and performance category seems to be the Crucial X6 4TB, which Amazon and B&H have for $149 atm.