I want to build a NAS using a raspberry pi. It feels important I should connect my HDD's via SATA, but the only way I figure out how to do this is with a compute module coupled with the IO board, and then a PCIe card that has SATA ports. This gets quite expensive so it's making me consider just how important SATA is for the NAS in the first place, so I'm wondering for the purposes of streaming HD video (not ultra HD/4k) how big a bottlekneck using a USB to connect to the HDD's would be? In this case too, if anyone happens to know, how important does the speed of the HDD become? Do I still want 7200rpm or would it not make a difference anymore?
Also, if anyone's familiar with a cheaper solution to get SATA connections with a raspberry pi, I'd appreciate it.