10 minutes of ultrasound to diagnose a serious illness can cost several hundred dollars in the USA
Maybe in a decade it can even be built into smartphones like a tricorder.
This device already looks like it can plug into a smartphone http://www.mobisante.com/products/product-overview/
The price in medicine is mostly not the hardware but the required expertise to analyse the data. Ultrasound imaging is not easy. The american health system is very expensive though, a ultrasound is around 50 euro's here.
That said, 3D ultrasound can have tons of other applications not just in diagnostic medicine. Real time surgcial feedback in soft tissue, yes please!
I can imagine engineers using it to examine materials, plant scientists looking at plant growth or builders using it to find out where different things are located in walls.
Chances are only a small portion of that is the cost of the ultrasound machine.
Also their raise ($100M) is an astronomical seed round, 100x what most companies would raise pre-product and pre-revenue in a first round. They clearly expect to deliver at volume on existing very high price points, or would not have raised this much money.
This isn't a few University kids disrupting an industry raising a few hundred k, this is an industry regular opening a division in it with $100M of his own money and that of a few investors.