A few weeks ago I picked up 2 TB TeraStation Live, and so far I have to say I’m very happy with it. I got it for $800 from buy.com, which puts the whole device at about $400 over the price of it’s 4 500GB hard drives. I think that premium is well worth it.
It was very easy to set up, at least for someone with a base knowledge of setting up a file share. The administration is done via a slow, clunky, but straightforward and ultimately effective web UI. I have set up a few different shares with varying permissions, and haven’t had any problems so far. Among its nice/key features are the fact that it is virtually silent, has gigabit networking, and isn’t too big, about the size of a mini-tower PC.