It's the same way with pinball restorers but they don't get off the parts unless they know you and you also have "trade bait".
It takes a long time to meet these guys and get into that circle, there are collectors and restorers and restorers that have the parts don't get off of them since you can't restore the games without the parts.
I don't ask here for parts for that reason, I figure guys that have these parts use them for their own restores and won't get off of them.
Not sure a similarity can be drawn between pinball restorers hoarding parts and longtime vendors/restorers in the muscle car hobby that actually turn over inventory. Small fry locals playing carrot and stick games, decided long before the Internet took off, didn't have to deal with them, and respectfully, neither should anyone. Many long timers like myself started working swappers in the '80's, running ads in the trader papers, going to regional and National shows, setting up meeting buyers, sellers and longtime folks that are still very active in the hobby. Its simple, for most there are tremendous repeat transactions, and none have to have a very expensively designed website, keep it updated every week, and charge extreme prices for common items.
Not sure how many dormant contributors there are here on this forum, ones that are well stocked in nice original parts, but can easily name off over a half a dozen on PY forum that are well stocked for certain year ranges of Pontiacs. Everyone of them is a contributor of true knowledge, above board, and each one of their word is gold, not game players. Over half of just that quickly thought of group, I've personally visited their shops or warehouses, and nice parts routinely come and go. None of us run Hemmings ads anymore, that was '80's... pre internet boards. This forum may not be near as active as PY, its just at some times the responses are some of the most naive, I've ever read when it comes to suggesting sourcing quality parts, and I'm not even going to go there with the support of the poor to medoicre quality (turn and burn) repro parts that are consistently put out by at least one national supplier.