Rakuten.com Shopping has the Western Digital Red WD30EFRX 3TB SATA3 64MB Cache 3.5" Internal HDD for $156 - $25 off with coupon code
NEW25 [Exp 3/19, new customers only] =
$131 with free shipping. Features a 6.0Gb/s SATA interface, 3.5" form factor, and is designed and tested for 1-5 bay NAS systems.