
We had quite an experience with the vendors in China. The deepest discounts came from the street market vendors (but then again, they started ridiculously high). On the other end was the government department stores. Even there, when we asked for a "discount" and were refused, they gave us a very nice little "gift" to compliment our purchase.
In between were the stores within stores that were run by independent entrepreneurs. They would reluctantly give a small discount. At the tourist attractions, the vendors were quite hardnosed, and bargained ferociously, and we were probably preceded by many gullible tourists.
Here are some of the general principles that we learned:

1. Do some research on larger items. Have an idea of what you would pay in Canada, and what the quality is. Look in the Chinese department stores to check Chinese prices. Hope to get a better price on the street.
2. Be wary if approached on the street. The quality may be nil, or they have stolen goods. One woman promised us "DVDs and Games, just around the corner". We went around, nothing in sight! She kept going, pulling us - we asked how far - "100 yards". We gave up after about 200 yards, as she headed down an ally!
3. Take a calculator to show the numbers to the vendors and avoid misunderstandings. Even if the vendors speak some English, it can be handy to convert currency for yourself. We often mumbled and put in random numbers, shaking our heads. Be careful to shield your calculator, because neighboring vendors cluster around, peering over your shoulder, and signaling the vendor your intentions!
4. Internet research will recommend different starting points. It depends on how high they start (you should know the value ahead of time), and where the vendor is. In stores and department stores, you may negotiate 10 or 15 percent off the price by offering 40 percent off to begin with. On the street, we would offer less than 10 percent of the initial offer. Andy bargained for a piece of luggage, which we had seen in the Department store for over 300 yuan. They started at 1200 yuan, Andy offered 100, and ended paying 200 yuan ($32 CDN)

5. We learned not to feel sorry for the vendors, and give them a good price. In spite of their frequent response of "no profit - no profit" and sad looks to our offer, they will not sell unless they are making money.
6. Relationship is very important. Take your time, make jokes and small talk, smile a lot, talk about your trip, how you like China, etc.
7. Learn some Chinese. Bargaining using Chinese numbers can win you some points, and may get a lower price when the other tourists around don't know the price you get.
8. Stick to your guns, be stubborn and persistent. If you do have a final top price in mind, stop there and keep repeating it. Discuss flaws and disadvantages of the item. Stop and look around at other items. Sometimes you could get them to throw in another item if you give them their price. At some point you can edge away, looking at neighboring stalls. Start to walk away, and listen to hear if the price comes down (it often will - we had neighboring vendors pushing us back to hear the latest offer).
9. Lastly, a bargain is a bargain. If the final price is agreed upon, honor this - don't walk away to check other prices. Your reputation can be quickly spread to other vendors, and suddenly, no one will sell you anything.