When creating a business plan Trade Associations are great industry information resources.
Below is a list of a few Trade Associations to help get you started.
The Census Business Builder is a great resource to find several demographic resources brought into one report by geographic location. Specifically, these reports will allow you to see annual spending per household on "Apparel and Services" and are meant to be used for business research.
The resources below are more general demographic resources that are very useful for market research.