If you have a media outlet (NYTimes, Google, etc.) that you would like to see prices for advertisements, try a Google search for [media outlet] AND "media kit" and then search for rates. See an example here.
MRI+
Requires a login with free registration. Focus is on print media, allows you to create lists of newspapers and magazines of interest then collect data on their ad rates.
Go to Reports: Magazine Pocketpiece to look at readership and median age of audience for individual magazines.
The US Census Bureau has the QuickFacts resources page with household, demographic, and basic economic data about a particular State, County, or City.
