To buy electronic, Hong Kong and Shenzhen are better choices. Guangzhou, Dongguan area are also good market to find clothes too. Won't you stay at Beijing?! Zhongguancun in Haidian district has big eletronics market, and you had better but things in large, regulate shopping stores. Xiushui Jie and Beijing Zoo are popular to find cheap clothes. As to the quality, it should pick among the great amount of stuff.