There is a cost, but I have added a Radio Altimeter, added Flymap L moving map GPS with Synthetic vision and in the process of joining the ADSB trial (the kit is in, awaiting CAA paperwork).
The cost of each of these is relatively low and "nothing" compared to the lives of any crew or passenger who will fly in my machine. The synthetic vision is not very exciting in S. England (too flat) but awesome when up in Scotland!