La Vega for fruits and vegetables (as well as everything else)! It's "the real Santiago," where many of the city's inhabitants as well as hotels and restaurants stock up on produce. If you like local markets, with their sites and sounds, you'll love this. You can take the yellow line of the metro to Patronato to get there. Nearest major cross streets are Antonio Lopez de Bello and Recoleta, in the Recoleta neighborhood.
For crafts, it's worth taking the trip out to Pueblito Los Dominicos in the Las Condes neighborhood. It's a collection of many traditional artisans in an area designed to feel like an old-world town. Great souvenir shopping or just an afternoon of window shopping in a nice area! To get there you can take the metro to Escuela Militar, then a taxi. The website is http://www.pueblitolosdominicos.com/home_.html