Of all of the boutique desktop assemblers, I find Origin PC the most interesting. Their offerings actually use the same pieces and parts that we like to use, especially in the custom water cooling area. Some of their offerings rival good custom water builds.
I expect great things from Corsair / Origin PC in the future.
I spec'd out a couple of different machines and then used newegg to price a similar (as similar as possible, their cases seem to be proprietary) machine and it looks like they charge about $1,000 for assembly/support/warranty, ignoring any below retail pricing they may get for parts. That doesn't seem much different than other custom pc shops.
I've never been interested in pre-built machines but I'd be curious to see a monster dual system streamer machine using the 1000D, mostly curious to see the price.