They most definitely have the right reasons for why someone should pay what they're asking. The reason #1, "we need to make a profit", is the biggest reason for the price. In reason #4 they clarify that reason by having tested that out of $10, $20 and $100 prices they made the biggest profit with the highest price.

The flimflam about updating the app just means that they don't wish to fire everyone now that they have a selling app, but instead will keep developing it with the hopes that it would sell even better.