I dont have a store nearby, so i do most of my headphone exploring by buying and reselling used headphones. Havent made a profit nor a loss in 20 or so headphones. But in my country (Netherlands) the market is pretty bad, especially with the higher end stuff. People try to sell their (ab)used stuff often for more than new price and get annoyed when you offer them a more realistic price.
Chicago FB and craigslist are 95% skullcandy, bose, jbl, soundcore, or gaming headsets.
I found a pair of K712’s for 90$ once, in rough shape, and the guy ghosted me.
I’d pretty much always rather create an open box discount for someone else by ordering headphones new online, trying them, and returning them.