It's cheaper to build a mini-server, if you you use really inferior parts, and have the skill/time to fiddle with linux to set it up. My only concern with the Drobo is the noise. Small fans tend to make high pitched whines that drive me nuts. I haven't heard a Drobo in person, so I don't know how big a problem this is. Part of the reason I pay extra for LaCie external drives is that they don't have shrill cooling fans.