My media server is largely ebay sourced, at least for all the interesting bits. The "server" itself was not, its a stock i5 that I bought from components.
For the drive enclosures, I found an ebay store selling Rackable SE 3016, which is a 3U half-depth enclosure with 16 hot swap SAS/SATA drive bays, a SAS 1 expander, a PSU and a SFF-8088 cable for $100 each (+insane shipping - I bought two, total cost was ~£500).
To hook this up to the server, I got a Dell branded "SAS 6GB 8e" controller, with two external SFF-8088 ports, again from ebay, £70 (free shipping!). The trick with this one is knowing that this is in fact an LSI SAS 2008 card, after some fiddling with flashing various BIOSes I soon had it behaving as an LSI-9211-8e in IT (infrastructure) node - meaning each drive connected appears as a drive to the OS, no RAID.
To house the enclosures, I use an IKEA LACK side table, which is exactly 19" wide, and has ~6.25U of storage. The servers sits on top of the side table, the enclosures inside it. I took the backs off the enclosures, and replaced the noisy data centre PSUs with consumer silent ones, and then put a fake back on the LACK table, with cutouts for the PSUs, and 2 huge 200mm extractor fans. This makes the entire thing silent, whilst still pulling through the same CFM that the original (Delta) fans did, but without the 80db whine.
I run FreeBSD on the server, using ZFS to manage storage. The current configuration is 8 x 3 TB + 8 x 1.5 TB, for about 31 TB of usable storage. Sequential read speed from the array is around 800MB/s, most writes are async, and there is an SSD for an adaptive read cache.