In China almost everything is bargainable (well, taxis, groceries doesn't count of course).

Once, when I was sitting in a pub with friend, I said the beer was too expensive here and suggested to look for another place. Even though I had no intention of bargaining the waiter came and asked us for what price we will be willing to stay. He ended up giving us 50% off providing we buy two bottles each.

That's only one example to demonstrate that in China you can bargain for anything, in fact most of the times you are expected to bargain.

Here are a few tips and pointers to help you with that.

1. Never feel bad for bargaining or getting something at a really low price. Remember - if the seller wasn't happy with the price he wouldn't sell it to you. It's part of their act to look unsatisfied.
2. When you are bargaining for an item and it's not going your way, look for the item in the neighboring stands. The chances are you will find it there. However you should know that the sellers in different stands usually work together so learn the lesson from the previous bargaining attempt. . Carefully inspect the items you want to buy and try to find flaws. Disappointedly point them out. This might cause the sellers to compromise more than they intended to.
3. Maintain your poker face. Never look too eager to buy. . When there is a little difference between the price you ask for and the price demanded by the seller, pretending to leave should do the trick.
4. It's very helpful to be able to speak Chinese. The less you look and act like a tourist, the better.