How about something with a little more oomph? Amazon is selling the Lenovo TS140 for $219
It's a little bit bigger, but has an i3-4130, 3 x 3.5" bays, plus 2 x 5.25" bays. It sips power and is very quiet. It has been sold for $199 in the past
$317 @ Amazon
Processor: Intel Xeon E3-1225v3 3.20 GHz
RAM: RAM ECC 4 GB DDR3 1600
Graphics: Intel HD P4600
Chassis Ports: 6 x USB 3.0 (2 Front, 4 Rear), 2 x USB 2.0, 1 x Serial Port (9 pin), 1 x RJ-45 LAN
Hard Drive Bays: Support for 4 x 3.5" Hot Swap Hard Drive Bays
Optical Bays: 2 x 5.25"...
I'd compare this to the HP N54L Microserver, not a real server that needs remote management/IPMI or anything serious. Looks like you can boot whatever from USB.
Throw FreeNas/ZfsGuru on a USB stick, install 4x4TB drives, and I think it would be an acceptable home storage server.
Ok, so it's not the 12-36 bay behemoths in other posts, but it can fit 4 drives (with a couple of adapters), idles at 25W and supports ECC. I think it's decent enough for a light ZFS server
Lenovo ThinkServer TS130 Tower Server System Intel Core i3-3220 3.3GHz 2C/4T 4GB No Hard Drive
It's unofficially supported. There's a menu screen in the BIOS with standard ECC options. I'm running a TA760G with an Athlon II 250u with 25W TDP and 4GB of ECC DDR2.
There's an extensive thread at silentpcreview about the A760G's ECC capabilities and power consumption