Great post by Marco Arment on handling customer comments. The bit about pricing complaints especially stood out.
Someone saying they won’t buy at your price is just one data point. Each sale of your appis another data point. If you sell 100 copies of your app and get 3 comments on Twitter from people saying it’s too expensive and they won’t buy it, I’d say you’re doing great.
Your product will never be affordable to everyone (and some of those who can afford it won’t be happy about the price). If you can find enough people who attribute more value to your product than what you charge them for it, you have paying customers and a potentially growing business.