TigerDirect now offers WD Red WD30EFRX 3TB 3.5″ SATA, 5400RPM, 64MB Cache NAS Hard Drive for $137.99 after coupon code EDG76777 and $20 rebate, this is pretty good deal. It's the lowest price I can find for this WD 3TB HDD, at least $20 lower than the next low price.
So if you want to expand your storage, it's a good idea to consider the WD Red WD30EFRX 3TB 3.5″ SATA, 5400RPM, 64MB Cache NAS Hard Drive. It is designed for NAS systems, the SATA 6 Gb/s ensures a fast and stable connection to the system. Very decent HDD.