Marine junkyards.
Actually there are such businesses. But even those are slowly going by the wayside. In Vancouver, Saanich, VIctoria, Steveston to speak of my general area there WERE a number of them but most are now gone.
There were several around Seattle and Bellingham area that are now gone.
No one wants the old parts. Most owners of new boats do not have the skills to make use of some of these things. They never grew up being handy persons.
Obviously there is still that type of person around but not as many so the used boat parts business can't make a living.
A lot of it was used by the small boat fishing industry to keep the boat going and we have all seen what has happened to that industry.
I search these places out. I actually have a very small one in GIbsons, Bitter End, but were it not for the new parts/supplies business end he could not keep going.
Both he and the previous owner like the used parts end but need the new parts end to survive.
Actually my boat still has most of the hardware installed on it new so I don't need much and since it is 44 yrs old it is almost a repository of old stuff most of which no one would want any longer.
Electronics are usually not highly resellable. Even I usually won't buy used electronics unless so cheap I can afford to toss it if it does not work out.
I have repaired SOME pieces in the past but it is not a hobby for me so although I used to understand a lot/some of it, it has left me behind which I am fine with now.
ANyway, enough.