Shopping opportunities and Bazaars in Istanbul are some of the best anywhere. Make sure to bring an extra piece of luggage! I recommend:
The Arasta Bazaar is a small crafts bazaar which has many small shops and also serves tea, coffee and snacks. I purchased some wonderful Uzbeki suzzanis from one of the stores. These are very popular textiles and are being used for throw pillows and to upholster chairs and benches here in the United States.
Explore the rug stores and ceramics shops surrounding the Four Seasons hotel. Gallery Ugur on Utangac Sokak No. 15 had nice ceramics and leather goods. It is out the door from the Four Seasons and straight down the street on the right. I bought a wonderful kilim rug across from my hotel at Artemis Rug Store, at Akbiyik C. Adliye Sk. No 11/14, phone 0212 517 8112. Ask for Murat Bor the owner. Walk to the Grand Bazaar and plan to spend a wonderful day exploring the thousands of stores. It is a covered bazaar with areas divided into several sections: antiques and carpets, leather and denim, gold and silver, fabrics and textiles, souvenirs and household goods and workshops. The pashminas are a steal! Take the tram to Eminonu. Walk the small side streets to the Spice Bazaar. This L-Shaped market is not as large as the Grand Bazaar and much more manageable. I loved buying spices and my new favorite olive oil soap.