Trade associations collect information on their industry. Sometimes they will provide free data, but other times you may have to contact the association directly to see what they have. Check out the website and look for links labeled "Research," "Media," or "Statistics." You can find trade groups listed in the two sources listed above and also use the Encyclopedia of Associations kept at the Reference Desk.
Trade journals can provide valuable data for the entrepreneur. Trade associations often publish them and may provide access via their website. You'll also find trade magazines listed in the "Industry References" section of Industry Surveys (NetAdvantage). Use the "Journal Finder" tab at our homepage, http://library.missouri.edu, to see if the Libraries provide access.