I'm running an ATX power supply externally for the moment, but did pick up one of these for when I go 24V in the future:
http://www.amazon.com/gp/product/B008X10HHE/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1
http://www.amazon.com/gp/product/B008X10HHE/ref=oh_aui_detailpage_o04_s00?ie=UTF8&psc=1