South Bund Soft Spinning Material Market – commonly known as the Fabric Market
No. 399 Lujiabang Road, nearest to Da Pu Qiao subway station on Line 4.
Anything related to fabric and tailoring – qipao, jackets, suits, silk, etc. – you go here.
Rule of thumb: You can get a men’s suit tailor made for 600RMB.
Of course it depends on fabric and style as well. You can even bring your favorite shirt and ask them to replicate it (much more effective than showing photos).