Yep. Been done. Mr. Mosquito is actually very good.
$800 is great for the machine that will be built from those parts, but $800 won't get you that machine. It will get you the parts with which you can construct that machine. The article mentions how much has changed in 15 months--that's about how much time it would take me to gather the minutes and hours to put together one of these homebuilt beauties. I want that computer and I want it for $800, not $800 + $1000 worth of my time.