About the video converter board / PCB in the picture. Looks quite simple in design and traces only look to be on the under side. Most (all?) of the parts are labeled on the top side. So we could likely reproduce it, but you'd need the following:
A very high resolution photo of the top side to ID the 2 black IC chips (inverters or flip-flops?), capacitors, resisters ect
A very high resolution photo of the back side to replicate the traces.
Once the traces are mapped out, there are places on the internet you can order batches of simple PCBs like this for under $20 each. Then you need the components, chips and VGA connector & soldering iron. I'm sure there's manufacturing shops somewhere (China?) that would produce the whole piece for a good price if you could get so many orders done. You could probably order 100 and what we didn't divide up here you could put on eBay and break even. I know lots of guys who do this kind of thing to replicate rare, fragile or obsolete parts for arcade boards they own. It's actually common in the retro computing fields as well.
BTW: This professional that did the conversion did basically the same thing or he designed it and had it manufactured.
BrianT
NOTE: The bracket to mount the monitor to the door is another custom you'll need to take into account as well.