When I see a garge sale sign that says 3 miles this way down a dirt road. I make sure to go.
Never had much luck in cities either but we haunt the back roads.
Bought a sporterized 7mm Mauser for $100. It had a set of Williams sight on it worth more than that.
Bought a NEF 12Ga that had only two shots through it, for $ 25.
Asked the people if they had any guns or such.
I've got around 50 airguns from yard sales.
Gotta go check the classifieds................