A few days walking around the Souqs and the Medina is probably enough. While it's not as busy as Thailand or London, it is still very busy. Streets are narrow, and it's often easier to walk then to get a taxi within the Medina with all the one-way streets. Most of my shopping I did at the 'fixed' price stores, but looking 'is free' in souqs and you can make your own mind up about the prices!