The $150 is a teaser rate.
From their email:
"A few weeks before we start flying we'll begin selling subscriptions. We will be rewarding our earliest supporters (the first 500), and those who recruit the most friends to PlaneRed with $150/month all-you-can-fly pricing. Obviously, the number of subscriptions we can sell at that price are pretty limited. So please - tell your friends to ensure that you get one!"