Spanx

Spanx began when Sara Blakely cut the feet off pantyhose while working as a door-to-door fax machine salesperson, investing just $5,000 of her savings to create a shapewear category that now generates over $400 million annually. Blakely's prototype—footless pantyhose with a reinforced waistband—solved a tangible problem for women without any existing market research. This makes Spanx 50% more cost-efficient than #2 Amazon's initial book inventory investment, since Blakely manufactured the first 1,000 units with only $5,000. By 2000, Oprah Winfrey named Spanx a "Favorite Thing," driving first-year sales to $8 million—a growth rate 3x faster than #4 Under Armour's debut year revenue.