U.S. Census Bureau (census.gov): A source for a variety of useful statistics, especially the Economic Census that comes out every 5 years.
Marketing - How is the product or service priced? How will it be distributed? How will it be promoted? Will it be promoted by the venture or an outside agency? What agency? How have you determined what amount to set aside for marketing? How have you determined product or service forecasts? Possible Data Sources: on-line searches; Amazon; local outlets; trade journals; industry attorneys & accountants; salespeople.
These highly trained professionals can also assist in calculating start-up costs, bringing in investors, and projecting profitability studies. Small business consultants also help you source funds by preparing financial documents presenting you in the best light possible to potential lenders and institutions. They can also help you devise business strategies that help you stay ahead of the competition.
Not surprisingly all these individuals have been in the business game for a long period and understand what they're speaking about. While you are in the beginning stages which may be just what exactly you will want, a professional available to assist you to on your way.