Keep an eye out at San Camilo Market — you're likely to uncover some treasure or trinket in one of its many stalls. After you've had a good look at the wares, grab a bite to eat from one of the nearby food vendors.
Located in Historical Center, this community marketplace is well worth including on your itinerary. But you'll find a great deal more to see and do in this area. Arequipa Plaza de Armas, Mall Aventura Porongoche, and Arequipa Cathedral aren't too far away from San Camilo Market.