You can always bargain with some small vendors of the stalls and shops in the scenic spots. Please be caucious of those street pedlars, you can see them in the streets or parks, please make sure what you get from these people if you decide to trade with them. We heard some tourists bought some very cheap stuff outside a park of Beijing, and the pedlar gave fake money as change. 

The prices of goods in the supermarkets or department stores are fixed, no bargain here.