Yeah, we've seen a similar question before, but this one's looking specifically at NAS devices that won't force you to liquidate half your assets to afford. We'll let David take it from here, and once you're done reading / responding, send in a question of your own to ask at engadget dawt com:
"I'm tempted to buy a NAS that centralizes all of my shared media, as well as act as a central backup. Redundancy is not a necessity as RAID0 will eventually fail and I'm not inclined to go RAID1 and waste the valuable disk storage space. I already have a few that I've been looking at, Buffalo's LinkStation and D-Link's DNS-323. What's people's opinion nowadays? Must-have features: UPnP support with transcoding (to media players, Xbox 360, PS3), torrent / NZB support with post processing, a nice GUI, a backup mechanism. Am I asking for too much?"
At first glance, we'd have to say "yeah, you just might be stretching it." But hey, maybe there's some perfect device hidden in the middle of nowhere that a kind reader will clue you in on. And if you're looking for dirt cheap, there's always the Addonics' USB-to-NAS adapter.