I saw these the other day and they seem like a pretty solid deal for some solid drives:
There were also some cheaper at ~$289, but they sold out:
Western Digital 0F38459 18.0TB Ultrastar DC... at MacSales.com
(*) 18.0TB Western Digital 0F38459 Ultrastar DC HC550 3.5-inch 7200PRM SATA Enterprise Hard Drive. 7200RPM Serial ATA HDD with 512MB cache. High Capacity, High-Performance, Enterprise Class Hard Drive. *System Pull, OWC Tested*
eshop.macsales.com
There were also some cheaper at ~$289, but they sold out:
Western Digital 0F38459 18.0TB Ultrastar DC... at MacSales.com
(*) 18.0TB Western Digital 0F38459 Ultrastar DC HC550 3.5-inch SATA 6.0Gb/s 7200RPM Enterprise Class Hard Drive. High capacity, high-performance, Enterprise Server Class HDD with large 512MB cache. *Factory Refurbished*
eshop.macsales.com