..... or anywhere else for that matter in a place where you didn't expect to find it.
While scouring the western Mediterranian these past two weeks, I found exactly zero prewar cards, but did find this item near the old Cathedral in Barcelona.
ATC Stock.jpg
Not too rare, and not prewar, but in excellent condition and priced right.
What have you found in your travels (hobby related of course) that popped up when you least expected it?