Thrift stores specifically in towns with lots of old people. Far from the interstate. They die and nobody wants their stuff so it usually ends up just circulating through the community. They reach that “fully picked over” state, except for usually the vinyl records.

Also, army surplus stores in towns that have bases. Military-grade generally means terrible quality but there’s lots of $20 steeltoe boots that will last longer that equivalent priced shoes from a bigbox store. And it’s in a town with a base, it will be cheaper because they’re always throwing away shit. I had a friend growing up who would dumpster dive the craziest stuff

Clothes thrift stores, old games or comics books etc local swap meet style where a bunch of people setup tables in a warehouse or tent on the weekend, furniture yard and estate sales