These days, Southwest Airlines is synonymous with low airfares and solid customer experience. But in the late 1960's when it was founded, the fledgling airline (then Air Southwest) was almost sued out of existence. Shortly after raising $543,000 in seed funding from investors (roughly $3.5M in today's dollars, inflation adjusted), the founders were barred from starting their disruptive low-priced airline by a restraining order filed by incumbent airlines Braniff, Trans Texas, and Continental. The money was raised and the license was granted, but Southwest's would-be competitors decided they didn't want the competition. 

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With $3.5m. Impressive.