Xiang Yang is not just a place to shop, but rather an experience. It is also known as the "knock off" market because of all the knock-offs you can buy there: fake designer bags, clothing, and watches. (U.S. Customs regulations permit an individual to bring back one each of various counterfeit goods, i.e. one bag, one watch, etc. for personal use.)
As soon as you step out of the cab, you will be accosted with "Bag? Shoes? Watch? DVD?" The market is mostly outdoors, with many tiny stalls and narrow, very crowded aisles. You must bargain for your purchases. A rule of thumb is to offer half, but this is not necessarily true. It could be much less. You need to have an idea what the item is worth. If it seems too expensive, it probably is. Don't be afraid to walk away because many times they will relent and chase after you, saying, "Ok, ok." It's all part of the game to get the best possible price out of you. They are very good at it too. Many shops carry the same thing. In order to make the sale, they will often run over to another shop (owned by some friend or relative) to acquire the particular size or color that you want. Besides knock offs, they also have many souvenirs, including silk pillow covers, tissue box covers, chopstick sets, silk/linen placemats, tablecloths, and tea mugs. They have just about every kind of cigarette lighter you could imagine. You can even get some souvenirs with Chairman Mao; my favorite is a watch with him waving.
If time allows and you haven't seen one yet, go behind the market to see the wet market. They sell fresh fruits, vegetables, meats, and seafood. Some of it is fairly exotic and maybe even live.
Xiang Yang market is located on Huai Hai Lu, which in itself is a major shopping street for the locals, and the prices will be cheaper than Nanjing Lu.