Answer

Go to the Virtual Business Library's Marketing Information section for links to useful resources including a link to the following suggested resource.

SRDS Media Solutions:  Choose your type of advertising source from the main page (ie Radio, TV & Cable, etc) then perform a search for your specific publication or station of interest to see available ad rates and circulation or demographic data.

 You may also want to consult the NYU Guide to Advertising Research and Planning which provides targeted resource and research suggestions.