This goes back to the days of newspapers, classified ads, and late night infomercials detailing how you can get rich from thousands of tiny little ads. One trick was to advertise a product at a specific price, saying "Send in your check or money order for $99 to P.O. Box..." and state that delivery was in 6 to 8 weeks. If you got enough orders, then purchase the product at a bulk rate and fulfill the orders. If not, send the payments back to everyone with some apology. Rinse and repeat with different ads at different price points until you find what generates the most profit.