Unless you're somehow able to buy direct from an authorized vendor (very tough gig to get) you're better off getting a nice custom one. Otherwise the Barebones kits are pretty expensive. Then you're buying proc, ram, and hd on top of it. Doesn't really pay unless you really want the experience of building it yourself, which I don't think is anything special.
If you want to check out some barebones setups, head to Asus or MSI's site and check them out, then google or ebay the model numbers and see what they're running. Otherwise places like ibuypower, cyberpower, or avadirect (and about a hundred other outfits) can build you the exact same thing for probably less money and certainly less work.
Asus/MSI also have fully prebuilt versions of the sames things available at retail, like was KC got, for example.