I think most collectors these days tend to have a stash of whatever parts they can source for there keeper pins, me personally I like to have mostly playfield plastics and ramps, as pins in collectors hands do tend to have a much easier life VS sited machines.
Agree. I bought anything AFM years back when the game was not that common locally, and parts hard to find. Glad I did, but haven't really needed much given that problems seem pretty rare in the home environment. And the heavy wear stuff (flippers etc) are readily available. Targets were useful, still have spares though.