Do what I did before I went off the deep end with storage. Antec case, raid card (optional, as ZFS may be a better option) cheap microcenter amd cpu/mobo bundle, and a bunch of 2tb HDD. This is what it looked like before I moved all my shit to a rack and became an unreasonable human.
http://i.imgur.com/I1w5B14.jpg
For the price of some of the easy nas options that only fit 2-4 HDD, you can build something that can fit 10 or so. Great if you want added redundancy.