The displays are already in production. There is no design work required, apart from interfacing with the existing autopilot. Mostly it is about testing the displays with the already installed equipment (autopilot, Air Data etc).
Considering each RK screen costs around US$50k for repair, the cost of this STC is quite affordable.
The Garmin panel in the other post is not IFR capable as the G500H is VFR only, so there would be extra cost. I was developing my own STC using another manufacturer, but I was having trouble keeping hardware costs alone below US$200k!
If AW/Leonardo can do the complete package anywhere near the price they are saying, I'll be extremely happy.
I know of quite a few 109E's that are flying around with one or two screens out already, so this becomes even more cost effective.
I do have repair cost for these screens somewhere. I would need to dig it out, but I seem to recall it being less than 10k. Don't quote me on that until I dig out the info though!