A fellow WIPper, though, told me about a secondhand store called Humana. I looked it up the other day and found there are a couple in Madrid. Friday afternoon, Izzy and I ventured to an Humana two metro stops away from our neighborhood. That day just happened to be 4 euros day; everything in the store was 4 euros. Everything.
I left with two items - a pair of shorts and a long-sleeved thin hoodie, while Izzy found five gems. It was just like your basic Goodwill, though smaller? And a bit less organized. Clothes were not organized by size in the least bit.
Then yesterday, while lounging around in Retiro Park with friends, somebody mentioned that there's an Humana in their neighborhood, and that they had seen '3 euros' signs that day. So that evening after leaving Retiro, we headed towards the Humana in Ríos Rosas. Sure enough, everything was 3 euros! Left with three finds that night, including a pair of pants.
Nice to know I'll be able to hunt through these stores throughout the rest of the year.