In what kind of police state would you find that a purchaser would need governmental permission to buy something from a willing seller?

In this one.

Of course, it’s all about corporations leveraging the power of the state to coerce their rivals. If you are someone who is against corporate power, you should be against government power, because as long as government has the power to do something, that power will be used on behalf of corporate interests who can afford to pay for the privilege. Corporations would have no more power than you or I if they couldn’t leverage the power of the state.