What to buy:
Provided you don't have claustrophobia or an aversion to people invading your space and hassling you to buy stuff, you can get some pretty good deals. When they first see you are a foreigner, the shop owners will try to overcharge you, but if you speak a few words of Spanish and can haglle a bit, you can get some prety good buys.
What to pay: Depends on what you want....and how good of a haggler you are (is haggler a word?)
Alcala is closed off to automobiles - numerous shops and restaurants are on this mall. The late afternoon is a pleasent time to shop thanks to the long shadows cast by the colonial architecture.