Istanbul has been known as a shopper's paradise for around 1500 years, since it formed the most important trading point on the fabled silk road, and to this day, visitors throng the grand bazaar in the hope of finding some bargains.
Wandering through the covered streets is a great way to spend a day in the city, and amongst the best buys that you will find are carpets, antiques and Turkish delight. Bargaining is considered to be normal, and may be conducted over a cup of coffee if you're haggling over an expensive item.
Just outside the city, you can find larger shopping malls - notably Galleria in the Atakoy district.
The Sultanahmet district of the city is designated as a tourist quarter, and many of the shops do not include the VAT on prices, meaning it's a good place to pick up some real bargains.
If you buy any antiques, you may need a permit to take them out of the country, so it's a good idea to check with the shopkeeper before you commit to a purchase.