EBay or Amazon, the seller is goharddrive. They're decommissioned server drives but other than run time they're practically new. Check both sites and their .com as well as the pricing isn't always in parity.
Make sure that's the seller if you get one though, they give a 5 year hardware warranty and will actually exist to honor it. Companies sometimes spin up a seller to unload their stuff then shut it down after enough is sold leaving the buyer with a useless guarantee.