where do I buy cameras watches computers etc. in Guangzhou?

Well, you can go to Tianhe Computer Shopping Mall. Alomost all the stores there sell many kinds of cameras and watches. These products have good quality and low price. You can go and see. The address is no. 502, Tianhe Road, Tianhe District.
About the watch, you can go to Zhanxi Watch Market near GZ Railway Station. This market is located at no.65, Zhanxi Road, Yuexiu District.