In Prague and Krakow it took some googling - apparently people in post-Communist Europe aren't too excited about giving things away, go figure - but we found a few secondhand shops where we were able to buy extra clothes for our forthcoming farm gigs. Patrick found some warmer clothes too.
In Barcelona we found a chain called Humana - they seem to be on every corner and their mission is pretty admirable. Patrick found a pair of jeans to replace his holey farm-riddled pair; he also found some comfy super-light cotton lounge pants. Jen was able to replace her extremely-over-mended-dying-a-slow-painful-death purse with a really functional shoulder bag; she also found a much-needed Sookie replacement (aka a wool scarf).
We paid about €20 in total which, for two pair of pants and a bag, sounds like a lot by American thrift store standards. But for a good cause we didn't mind. If we bought it all new it would've been five times that, and besides, after four months of being completely out of our element the nostalgic browsing experience was almost priceless in itself.
So yeah, Humana. If you're in Barcelona, stop in and check them out!