Without wishing to derail the thread further, I was thinking of the many times over the years I've gone to local hamfests/boot sales looking for old transcievers to part out,.
Some Hams (more commonly in the USA than in this country),get quite "aggro" at the thought of people buying radios,parting them out then selling the parts.
Admittedly,there are some "vultures" who make a big thing of this,buying radios in perfect operating condition & selling the parts at a substantial "markup".
This has two effects:
(1) It reduces the number of functional secondhand radios on the market,pushing up prices.
(2) It makes refurbishing of existing radios more expensive.
I'm not suggesting that you are one of the "vultures" referred to,but maybe some people have incorrectly assumed you are.
Demanding you show a Ham licence is a bit silly,as some of the "vultures" are licenced Hams.