We had the Pentax 645D for a long time, priced just a little bit above Nikon D4 and Canon DX. Now the 645Z is almost here with an even lower price tag. The old 645D was a very good camera and the 645Z will also be avery good camera.
It is very obvious that the sensor cannot be very expensive if it is offered for around 8K with a complete camera. Keep in mind that Pentax still with all certainty makes a profit. So it is quite probable that the sensor cannot cost more than 2k$. Also most of the R&D has done by Sony.
So very clearly MFD prices are not motivated by cost of technology. It is in a sense similar to the Hasselbling products, Hasselblad takes perfectly good Sony cameras (NEX 7, RX100 and Alpha 99) add some cosmetic changes and sellt at 3-7 times the original Sony price. Better camera?
Now, there is an other side of the coin. A company like Hasselblad or Phase One need to feed a lot of people.
They could, with certainty, produce at much lower prices and sales would be much higher at those prices. But, to do that they would need to expand production, which would be very expensive. Without expanding production they cannot make ends meet with much lower prices.
Very obviously, a digital back could be made for as little as 4-5K. A digital back is essentially just a sensor mounted into a metal box, a display on the back and some electronics to integrate with the different MF systems. So anyone could make a low price MFD, and sell a lot of them, but the only backs we can buy come from Phase One (including Leaf and Mamiya) or Hasselblad. I don't know if there are still Sinar backs and backs from Jenoptik. It may be that MFD is not lucrative enough for competition to develop.
It's really interesting to see how many people expect the world for $2.59. Before the 33x44 50mp Sony sensor, dmf was just expensive. Now everyone expects 35mm pricing. Watching the comments on a few other blogs, people have unreal expectations. Hasselblad has done a horrible job marketing the H system. PhaseOne did their IQ260 World Tour last year, and from what I saw, it got a fairly good turn out for folks. Locally, Glazers did a presentation with John Keatley on the H5 and it sold a couple of kits. The interest is out there, but I don't see Hasselblad doing what it needs to in order to get sales.
In some ways, I would like the H4x to be cheaper, sold in a kit with a 120 back and the 80mm lens. But then since Hasselblad doesn't make an open system digital back to offer as a 'next step', they'd need to.