Just a quick off-the-cuff build idea:

Zotac IONITX-F-E motherboard; I love these boards, they're low power draw, but pack a lot of punch. This one has a 16x PCIe slot. Into that I'd put a SATA controller with at least 8 ports. What ever case and power supply you want. Even though that board is a mini-ITX, it's screw holes match up with ATX so it can be used in normal cases. I'd go with something which has 8 hot-swap SATA bays, and an open 5.25" bay for an optical drive. The onboard SATA would be for the optical drive, and I'd probably put one fast (SSD if you like) boot drive in for the OS, leave the hotswap bays for media. Add add the drives and some RAM, and you're done. That give you N WiFi, gigabit Ethernet, HDMI/DVI/VGA, sound over HDMI, optical S/PDIF, and 5.1 analog. Along with enough bays for 12 TB of storage today, 16 very soon.

The base system, with just the boot drive, DVD burner, and 2 GB of RAM, and OS could be had for about $700. Then about $100 for every 1 TB after that.

Pioneer PDP-5020FD, Marantz SR6011
Axiom M5HP, VP160HP, QS8
Sony PS4, surround backs
-Chris