Headline: Libertarians be like Picture of disugested women next to "Tyranny.gov" Picture of intressted women next to "Tyranny.com"
it's easier to pick a different corporation (i.e. don't buy from them)
This argument also falls apart when the thing you want to buy is essential and/or all of the companies selling it are horrible (or the very concept of selling it at a profit is horrible), e.g. health insurance, water, housing, staple foods, and so forth.