I don’t know if this topic has been touched before, but is there certain flashlight brand/models that is no longer sold or discontinued that people would still purchase if someone was selling it? Kind of like antique resale but for flashlights. If so what would be the one you are looking for?
Liteflux lights used to command a crazy premium, the only light I know of that is worth sustantially more than it’s original price.
Otherwise, lights with okay resale value, despite being “old”:
Sunwayman V series
Sunwayman M series
Rare lights:
Lummi lights
Original Peak Eiger/Logan/various mountains. They did a 90 degree adapter which I’ve not seen for sale for a long time.