the ReadyNAS Duo, diskless is on Amazon for <$300. Combined with two large SATA drives, with RAID1 you have pretty good data redundancy. External USB backup is a must, with rotating offsite storage in case of fire or theft.

My Sonos system is fed by a ReadyNAS 1100 with RAID5. IMO, the readynas SW has matured and is pretty good. Don't expect fast cpu(intel) for cheap prices, though. Their PRO line uses Intel CPUs for computing on the file server, if you need it. Sonos doesn't really need it, so I don't care.

I would consider doubling my disks and swapping off site file backup with a fellow Hitchhiker (only FLAC and MP3, photos). PM if interested. My CD/ROIO collection is about 700 Gb, so Mozy/etc is uneconomical.

Primary: 818v3+ID41, M6 stereo pair, M SpeakerLink cabling, Sonos+96kHz Cullen, silver DSW
HT: Marantz prepro, 271, DSP3300, 8K SE FL/FR pair, DSP M6x2, DSP320x4 (ceiling), black DSW, 520 RL/RR rear in-walls
Living Room: G65, 640 L/R in-walls, UHD722, MS600
Vac. Home: G61, HD621, 4xDSP3100, DSP3100HC
MDMS:NUC/ROCK+TrueNAS Core 12.0 ZFS file server