The price of a Qipao may spread from CNY100 to over CNY1,000 in terms of different clothes materials. On Maoming South Road, you will find many tailor's shops for making cheong-sam.
Here are some tops one:
Jin Zhi Yu Ye (金枝玉叶): 72, Maoming South Road. CNY1,000~5,000
2002 Shanghai: 5, Tianzifang, Taikang Road. CNY1,000
Gu Wang Jin Lai (古往今来）: Changle Road. CNY400~1,000
Xin Ni (辛妮): 231-233, Changle Road. CNY500-1,800

For cheaper ones around CNY100~500, please go to the Huan Long Department Store located close to Shanghai Railway Station, or the Shi Liu Pu Material City (168, Dongmen Road)close to Yuyuan Garden.