I prefer it greatly over a proprietary power supply. High end efficient used +12V server power supplies will beat new every time, not only in price but performance as well.

Buy yourself an automatic wire cutter/stripper machine, some 5000ft spools of 16awg primary wire, reels of crimping pins and bags of end connectors. And you will never have to buy a PCI-E cable again, and you can make them just the length you need.