This topic has been discussed over and over.
Like Rainer said,it would not be viable to make a 28mm lens to cover 6x6.
I can't imagine people paying $10.000 USD or more for a lens.
The 28 HR Rodenstock already has a serious price tag.
Imagine a retro focus 28mm for the Hy6?
I've already been told that the 35mm AFD-Flektogon will be close to $10.000 AUD.
Especially with our current exchange rate.
3 months ago our dollar was almost equal to the US,it has since dropped 40%
Regards,
Willem.