I might have a SnapServer 1100 surplus here real soon...
(Don't get much smaller than that)
All the branch offices were run from SnapServer's when I did a brief stint in Northwestern Mutual's IT dept. They worked pretty well. Unless they've got multi-drive units though, I don't think I want a single-drive NAS. Might as well just buy another external USB HDD and save my money. After having two HDD's die the same day out of five functional PC's in the house, and those two HDD's having critical photos and video on them, I now strongly feel the need for at least mirroring, if not actual RAID 5.
The nice thing though is if you're too lazy to wire your house with Cat5e, signing up with AT&T U-Verse will get that done for you for free.
I still lament the fact that backup tech has not kept up with drive technology. Unless you want to get into ungodly expensive exotic and semi-proprietary optical disk/tape technologies, there is
nothing that can keep up with 1TB/$100 HDD's, except for just juggling those same HDD's in a RAID and praying that no more than one fails at a time.