After MIR price is only useful if you are buying a couple since almost no MIR will let you get a rebate for 12 units. You'd probably be better off (and get a much better supply) if you bought four of Sidehack's DPS-2000B boards with cables for $366 along with four PSUs off eBay for $120, and ran four boards off each one.
Good point. Looks like those boards aren't available yet?
Here's the link to the pre-order for those that want to investigate.