We are talking about way more than a couple hundred dollars. I have 16tb of NAS storage that I put together for right at $1000. And, I didn't go for the cheap route. My drives are WD Reds and one NAS is a QNAP and the other is the latest WD box. Tell me how I get 16tb of storage protected by RAID 6 for $1200.
Build a cheap Linux box running SnapRAID and fill it with 7 x 3TB Toshiba consumer HDDs @ $90/per. If you have an old PC lying around then all you need is the HDDs and an SATA adapter card for $20.
But I agree, how to protect the data is a huge factor to consider when building a server or NAS.
Quite frankly, RAID in any fashion is probably overkill for home use. Most people would be served just as well by just pooling drives JBOD style. But they still need backup in some fashion. A 2nd NAS, of the same size, on the other end of the house or in the garage would be ideal, but hardly practical for most people. Certainly it wouldn't be the most cost effective solution for all but a tiny handful.
That's why I went FlexRAID and their version of RAID 6 (unRAID and SnapRAID would be just as effective); One server that can handle 2 simultaneous HDD failures. I went this route over a hardware raid or ZFS solution with this in mind:
#1 - I know that I have had only 1 HDD failure in the last 12 years that wasn't due to being dropped. So my odds of having an unrecoverable crash is small enough with RAID 5, let alone RAID 6.
#2 - I can expand the array by simply adding more drives. No need to break up the array or worry about pooling multiple arrays.
#3 - If, somehow, I get 3 simultaneous drive failures I only lose the data on the drives that actually failed. With FlexRAID, unRAID and SnapRAID, I can simply break up the array and import the drives into window and use the drive as a standalone. For this reason I don't swap smaller drives up to bigger HDDs, I just add more and spread the data out across more drives. If I end up re-ripping I don't have to re-rip everything.
#4 - My backup is a 2TB external HDD. I can fit all of my photos, Home Videos, Documents and Music on it. Movies can be re ripped but knowing about factor
#3 this isn't as big a task as it would seem.
robnix nailed it on the head. At some point a full backup just becomes impractical, especially for something that would not alterably change my life if I lost it permanently.