The River of Hearts do collections of quality clothes that they sell somehwere/somehow to raise funds for their fanastic charity work. Try contacing them at riverofhearts@communitycenter.cn or phone the community centre on 5030-3313 or 5175-0510. They have drop off points for clothing all around Shanghai.

Or the "Charity Shop", located at No.235 Xizhimennei Dajie, in Xicheng district. Half the space is given over to a grocery store, selling eggs, vegetables and drinks, and half sells donated goods on behalf of charities, including stationery and decorative items.