wigglyamp
You make it sound so difficult and so complicated that for course your average Joe will gladly part with thousands for the avionics god to do his stuff. The reality is that your average Joe could learn how to wire up an entire aircraft, including the avionics, in not very long at all. Fortunately the LAA system allows this to happen and yes I have done 95% of the wiring on my aircraft, including a glass panel and a navcom.
I recently demonstrated to another owner what work was required to upgrade his plug compatible mode s transponder. When he found out he had been charged £1000 plus vat for an installation which had taken about 10 min he was not very impressed! The paperwork / mod fee was separate, the £1000 was just for installation which requires no special tools, no wiring and the unit tests itself and allows you to enter the id and check the mode c from the front panel etc…
Rod1