What’s the catch? This is the best deal I can find on the internet by a fair margin. This seller has an amazon store page as well and seems to have a good reputation on both. The seller claims its a new HDD from a reputable brand and offers a 5 year sellers warranty.
I bought four of those drives from SPD to put in my NAS. After testing and burn in, one of them started failing tests. SPD had me send the failing drive in and they sent me a new one. Otherwise these have been great so far.