noone picks numbers out of thin air. they do a/b testing to see what gets the most revenue. Usually at $9...you only sell twice as much as you do at $30...so

noone picks numbers out of thin air. they do a/b testing to see what gets the most revenue. Usually at $9...you only sell twice as much as you do at $30...so you actually lose money. That's because to most people $30 or $9 makes very little difference