Once you see the uphill road, you realize you're better off starting from scratch and writing the product yourself instead of depending on OSS. For some noncritical aspects, it's fine, but then you get into the definition of "noncritical" :-)
It also depends on the class of your device (A, B or C in 62304 parlance) how much rigor you must put into your software process.
Ultimately it didn't matter much for our beauty product but it would be a big problem if we tried to use them for imaging.
At one point in time, I had a number of people in incoming receiving working for me. We had to do all kinds of quality control on incoming components, such as castings, PCBs, etc. We had automated measuring machines, etc. It's all very expensive to set this stuff up and staff it.
We also had to use an XRF gun on parts, to make sure we weren't being shipped non-RoHS parts.
As I remember, one of the add-ins for our Agile PLM system (Agile is an Oracle product) was on the order of a few hundred thousand dollars for licensing fees and setup, not counting the months of consulting time necessary to load bills of materials, etc., into the system.
Just to point out injection molding, 3D solid modelling, and CNC machining don't have to be super expensive these days.
Large volumes, and especially high end stuff... sure that takes a lot of up-front cost. But for smaller volumes (eg prototyping, short run) the costs are very reasonable now.
It seems due to continuing development of Open Source hardware and software in these fields, which created good virtous cycles for them. Hopefully this continues... :)
Note - saying the above as someone who's into 3D solid modelling and CNC machining already. Haven't gotten into injection molding yet, but it's on my personal ToDo list for not far off. :D
The post is necessarily incomplete; I don't think I can give you a full appreciation for all that is involved. And I don't wish to give the impression that ultrasound is necessarily more complex than other imaging modalities, such as MRI, PET, etc.
I wouldn't rule out open source, and many open source tools are used in the engineering process (e.g., gcc, git, etc.) I don't know about including open source components in a commercial code base, though. The lawyers usually ran away screaming whenever we would suggest using any open-source code.
Certainly the high-volume electronics industry makes components that are used in ultrasound systems. Some of the ARM SOCs, for example, and I suppose, some of the FPGAs, DSPs, etc. There are also a number of custom components, such as ASICs and combined analog-digital parts that show up in the so-called "front end."
The companies I have worked for designed their own transducers. That really is a science as well. Making a transducer probably involves at least 100 - 150 process steps, and some very expensive equipment (dicing saws, for example.) You also often have injection-molded parts (e.g., the transducer handle itself) that are expensive to produce (the molds for the injection molding machine are done with 3D solid modeling tools, then CNC machined from steel, etc.
You also have whole departments of people that work in "Regulatory Affairs" and/or "Compliance Engineering."
You also need to employ people to "optimize" your ultrasound images, in each of the different modes you might support: B-mode (2D), doppler, M-mode, color power doppler, etc. You also have things like harmonic imaging, etc.
Then there is sending images you have collected off to the various PACS systems that hospitals have. This usually involves a complex protocol known as DICOM.
Ok, I'm out of gas for this comment. Again, not trying to drown you in jargon, just suggesting that there is a reason that new ultrasound machines tend to be pricey; that reason is that NRE (non-recurring engineering) is very expensive, actually building the boards is expensive, shipping the systems and maintaining them in the field is expensive, and maintaining all of the other systems you have to have in place to be a viable ultrasound company is really expensive.
Hope this helps; thanks for letting me share a bit of my experience.