This store at Madrid's Plaza Mayor has a great assortment of traditional headwear that reflects the…read morevarious regions of Spain. Surprisingly, despite the location, it was also rather reasonably priced.
Even here, I was happy to find the Elosegui brand of headwear, which was founded in 1858 in Tolosa, in the Basque Country (northeastern Spain). Various Basque headwear is pretty hard to find anywhere, especially of good quality (this was made out of wool to keep your head warm in the winter), so I was pleased to find it in Casa Yustas and was able to buy a particular one that is typical of the Basque country's Pyrenees region for myself (boina pirineos, yes, that specific!) - both as a souvenir and as something I can wear often!
Customer service was a bit worn because of the gamut of tourists outside the doors, but also friendly once they see you're interested in actually buying something.
I would peruse through the selection here again if I do come back to the area.