Somehow, we kept ending up on La Rambla. It's the most famous street in Barcelona, and there are a ton of street performers there as well as stands. It was actually kind of interesting because they were sectioned off by what they were selling: first, we walked by a bunch of people selling birds, rabbits, hamsters and chipmunks, then came a block or more of flowers, and after that the souvenir/newspaper stands.
I really wish I lived in a city sometimes. A friend of mine lives in Bamberg, and while it isn't a big city, even they have flower stands like this which are much cheaper than flower shops. Every time I finally end up in a city where they have them, I can't actually take advantage of them because I won't be going home anytime soon. Plus, they have a much larger variety than any of the flower shops I've seen in my town.