Start with a unrealistic low price, so maybe 30RMB for the chest set. It can happen that they say "go away" and thats it. But most time they will start barging. You need time for this, could take about 10 minutes to get it for a realistic price.
The sellers have a fixed salary, so they can sell it to you for 100RMB if they like you, or they could sell it for 800RMB if they dont like you. They will get the same salary. So be friendly to them.
Because there are people like you, they have a easy game and foreigners will always get a to high price
And dont look at the brand. Everything you got in this factorys are copies, so he price will come from the quality, not from the brand.