Hello:
You can buy those fashions at Zhongshan balu or Zhanqianlu.Of course, you can change dollar in banks,but the rate of the black markets is usually higher than the banks,I know there is a plase near the Dengfeng hotel and there are some Tonggan people are engaging in those kind of things there ,maybe you can get the higher exchange rate there.
The wholesales markets will be opened after the fourth week of this month.
There are a large variety of shose are for sale Yaotai

Good luck!