This thread may help:
viewtopic.php?p=131017#p131017El Mercado is just fantastic (though not specifically Iberian). There are good quality Spanish meats and cheeses at Fox and Obel and even the Marion Street Cheese Market (Oak Park). If you get friendly with the bar staff downstairs at Mercat, they may sneak you some mise from the kitchen for very specific items (percebes, squid ink, you didn't hear this from me). Ba Ba Reeba cooking classes (about $40 per person) are another good way to learn technique and pick up some ingredients and recipes that they send home with you. I order my paella pans, cazuelitas, and strand saffron online (various sources). Sarah Jay is great:
http://www.paellapans.com/Penelope Casas, memories from several long summers, and an archive of Gourmet magazine recipes (some are online, some clippings) are my primary sources. Good working thread by Mike G.:
viewtopic.php?f=16&t=8341&hilit=tapasEmilio's in Hillside is slow these days, and the namesake spends more time there than the others, so you can catch him for some lore on a night early in the week (or call in advance to find out about his occasional paella / tapas classes).
Buen provecho!