I knew a number of contractors who would go to the old Maxwell St. on Sundays to buy back their tools and equipment which had been stolen during the week. Also, when your hubcaps got stolen, you could always find perfect matches there
Sometimes only one or two hubcaps were stolen, and, lo and behold, they'd just happen to have only one or two where were exactly right.
I also recall tables with stacks of car stereos, with loose connector wires hanging out of the backs.