What is best solution for 7th Sata connection - ASUS p8Z68-V

Have the following and want to add a 7th sata connection for an internal HDD. What is the best solution? PCIe to Sata card? What brand is known to work? Any to avoid? Internal USB to sata an acceptable alternative?

ASUS P8Z68-V/GEN3
I7-2600K
Vertex 3 on sata 6gb port
BD drive on sata 6gb port
4 internal hdds on the sata 3gb ports

Want to add a 5th internal HDD - Hitachi 3tb 5400rpm, so need a 7th sata connection. Computer is at location out of town, so I would like to make sure I get components that will work since only a few trips a year to this location. Drive will contain movies... so don't think speed is a big factor (?).