The mention is the prices of Cables vs Amplifiers promoted me to do a quick comparison - of the Price of Naim NACA5 vs the NAP250.
This is based on published Naim Audio Price Lists, from 1992 up to 2020.
In 1992 - A5 was £4-35 per meter - NAP250 was £1398
In 2020 - A5 was £35 per metre - NAP250 was £4099 (yes - I know this is the 250 DR)
A5 has gone up by around 700% or 8 times.
(the biggest increase was around 2013)
The NAP250 has gone up by around 190% - or 3 times.
(the biggest increase was around 2004)
I would say that the price escalation of the 250 is fair, over this length of time.
The price of A5 though, cannot really be considered fair, in my view. YMMV.
(for a Should Cost, just look at the price of Linn K20)