Found these whilst snooping around ebay
Refurbished HGST 0F18370 6Tb Helium 7200RPM SAS 6Gbs 3.5" Drive, QTY discounts! | eBay
Messaged the seller and they have roughly 1600 days powered on so a bit high but going strong as they are well past the common failure date ranges, seller is accepting offers on them too but haven't tested just how low they will go.
Refurbished HGST 0F18370 6Tb Helium 7200RPM SAS 6Gbs 3.5" Drive, QTY discounts! | eBay
Messaged the seller and they have roughly 1600 days powered on so a bit high but going strong as they are well past the common failure date ranges, seller is accepting offers on them too but haven't tested just how low they will go.