Plus, the easiest way to communicate with a business user that you are better than Balsamiq is to charge three times what they do. You and I know that Peldi is the thought leader in this space. Your customers, overwhelmingly, do not know who Peldi is.
They have two data points: 1) what was on the 5 minutes of Google searching they did (and I'm overestimating by a factor of 10 for many customers) 2) what you are charging. If Balsamiq charges a third of what you do, well, clearly that must be the inferior knockoff which is only used by ramen-chomping MIT students, not what we'd trust our client relationships with.
(Balsamiq is, obviously, not an inferior product and I make lots of money for my clients using it. But if you put a gun to my head and said "Compete with it", I'd start by charging a lot more.)