I'm not going to go into the fine details of the MDAC2 design - the design is proprietary and I've obviously spent a significant portion of my life over these past few years working on the design so I have no intention of revealing its more salient design IP.
I find the tone of your questions rather offensive and I'm disappointed in you, the fact you ask these questions just highlights how little you understand.
WRT to the transformer costs, these are Custom designs - and in fact the next (and hopefully last) design prototypes are the 5th or 6th design iteration - (maybe there have been more iterations - we started out working with Lundahl Transformers)...
The design is very unique and NOT your standard I/V transformers (in fact other "I/V" transformers I'm aware off do not operate in Pure current mode). Due to the currents and impedance's involved in the MDAC2, these are LARGE transformers - soo large that we have had to machine the top off the plastic Bobbin to fit within the MDAC chassis. I've certainly have never seen any true "IV" transformer designs - only rather Amateurish applications of transformers in so called I/V mode - and its technically arguable that while they do transform impedance's they are not operating in true current mode - rather some Amateur DIY applications that have failed to understand the requirements of true I/V conversion (Virtual Ground - no "voltage" swing).
WIth transformer Quality - size DOES matter and these are the largest transformers that can be squeezed into the MDAC2 Chassis.
Again - I don't appreciate your "shit staring" WRT the LCD pricing, the panel I'm using costs over GBP225 including VAT (1 - 10 Pcs), sure 100pcs order will be cheaper maybe around GBP180 (with VAT), welcome to the cost of small scale European manufacturing... I sincerely doubt I'll be in a position to place an order for 100 panels in a single shipment - that's GBP 18,000 just for 100 LCD panels!!!
Please go ahead and fit a 6inch phone display on the MDAC front panel - and while your at it, please also find the panel driver information (EE and software) for said panel with capacitive touch interface (must be parallel or LVDS interface (not MIPI).
I need the Linux software drivers for the LCD panel and Touch interface.
So when you have a High resolution IPS LCD panel that physically fits across the front of the MDAC front panel, has LVDS or Parallel interface, with Capacitive touch, has hardware interfacing datasheets (not propriety information only revealed to larger companys under NDA), has drivers for both the LCD panel and Touch panel for Linux - THEN we can talk (I'd be very interested as I still have time to change the design)... But do not waste my time with some random panel that will not even fit on the MDAC front panel that you've seen on EBay, one that undoubtedly has no hardware information / software drivers etc...
I'm sorry to others here for the tone of my reply, but I've spent a huge personal fortune and time on this project and obviously I don't appreciate being second guessed in a "shit staring" manor - there was no positive point to the question, its only purpose I can see is to cause trouble.
To "Finance" the software development of this LCD panel for the MDAC2 project, I'm having to spend 2 weeks in China / HK as an "Adviser" introducing a local European company to Chinese vendors / production. This is 2 weeks away from Renata, Pups and the comfort of my lab so I can "deliver" important finishing features to this project... Then I get questioned about the cost of various parts...
I detest the idea of having to spend anymore of my life in China, but I'm single track minded in delivering the very best possible design, even if I have to "sell my soul" by travelling to Asia...
There is an upside to the trip apart from the "Direct" benefit of having the software developed for the MDAC2 Touch panel - that while I'm in China I also plan to visit the Detox chassis CNC vendor...