where can i get cake ingredients in guangzhou?

You can go to the North Side of Jiangnan Avenue, Haizhu District. This area has lots of stores that sell may wedding products. Most of them have cheap prices and good quality. You can also find some wedding cake products.

According to the book "A Businessman's Guide to the Wholesale Markets of Guangzhou" you should be looking at Guangzhou Nantai Kitchen Accessories Wholesale Market 南泰百货批发中心

Transportation: Exit D from Jiangtai Lu Subway Station, will bring you out at the very bottom of Jiangnan Da Dao. Walk fifty metres to the first corner and turn right. This small connecting road will take you 200 metres up to the main intersection with Jiangyan Lu. Turn Right again and the rear entrance of the market is about fifty metres across the road.