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Determine who are qualified buyers of your product. You need this information to obtain the qualified data. Location also will impact the data. If the buyers are government or a publicly traded company then there are many sources. Publicly traded companies have to disclose a lot of data in reports as well as government reports for businesses doing business with government. As to private businesses there are sites that sell the data but the issue is reliability of the data from private sources. Depending on the potential value of a transaction you may want to hire an investigator to assist you. There is no easy answer when dealing with private entities.