Inspired by the legend http://helmer.sfe.se/(external link)
I built my own back in June.
Ikea + Fedora + AMD AthlonII 4 core processors + Gigabyte MA78LM-S2 motherboards + netgear ethernet.
For the price of a shiny new mac I’ve got a 6 machine renderfarm with 24 cores. The modular nature of the shelving keeps everything organised. Just got the local garage to drill some holes for ventilation and the power buttons. Had to learn about Linux which was a pain but now I can run everything directly from my pc which is on windows using samba and vnc.