Sure a GA setup with a radio stack would be nice. Nothing is really there in the market for the hobbyist.
To be honest now I think about it there may be room in the market for a bare cockpit but it would need to accept gauges, displays and controls.
In addition it should have some instructions or a guide on how to integrate your controls and instruments into the cockpit, full of diagrams and pictures.
Finally it also should include a list of suppliers for say LCD panels, interface cards, switches etc etc.......
My point is don't just offer the cockpit but give the cockpit builder a foundation for which they can build upon.
Another 2 cents
