Not to be harsh, but that's not really a very good example of doing a home lab on-the-cheap. You can pretty much buy his "lab" off-the-shelf on ebay: One used C6100 chassis using L5639s easily hits a lower price point than his four micro-ATX "nodes". Plus it provides housing for 12 LFF disks, has more networking, is easier to add 10Gbe (or even Infiniband) on the cheap, etc. Add the same 10Gbe switch he used and you've got more horses in 3u for less money and packaged better than his whole messy stack of boxes.
It is nice to see it written up in a more mainstream media source rather than just in the enthusiast forums and/or geek-rags.
Oh I totally agree that he could do it for A LOT less money but he seemed to want to still have the enterprise support and also gear that was similar to their production equipment but I wager you could do something similar for like a third or half of what he paid