I picked up 2 of the Minolta/ Konica batteries for the 7D and I can say without a doubt that they are the exact same batteries as the $160 Mamiya units. Same specs, color, caps, etc. I charged one last night and popped it into my ZD back and it fired right up.
Best part is that you can buy them from B+H for $10! The counter guy at B+H said they have something like 500 of the Minolta branded battery in stock. The only caveat is these batteries have been sitting for awhile so some might not last as long as the newer knock-offs.
I'm honestly a little p.o.'d at Mamiya for pricing the ZD batteries so ridiculously high.