While these are easily available online, some of them are way better than the others. A lot depends on the approach that goes into writing the business plan.
"Plans are useless; planning is indispensable," according to Dwight D. Eisenhower, then Commander of the Allied Forces in Europe during WWII. Now, you may be in total agreement with the first part of that statement, but you are really not convinced of the truth of the second part.
James J. Hill Reference Library (jjhill.org): One of the nation's premier business libraries to bring you FREE and affordably priced tools and resources you can use to create a better business plan based on relevant and credible data.
American Demographics (adage.com/americandemographics): Just as the title suggests, numerous free reports about consumer demographics in the U.S. nationally and by statistical area.