One piece? No, they will not give the wholesale price for just one or two pieces. It will be higher in price if the seller think you are not buying in bulk and foreigners I am afraid. What you should do is try best to negotiate or get around for other shops. For nigth market, it should be Beijing road and Shangxiejiu Road, which are still busy commercial street at night. Beijing Road can be arrived by Subway at Gongyuanqian Station. Shangxiajiu is not far away and you can use taxi to get there.