Have you put some time into thinking about how your product can provide a meaningfully different user experience than the competition? Do you understand what the competition really is? Telling a story about why users will pay for your product is part of making a compelling business case for the next round - your margins won't matter if nobody wants it.

You don't need to spend thousands on research to start getting a better sense of what problem you're solving. Send a note to http://uxhours.com/, or pick up a book on understanding user experience. Mike Kuniavsky's 'Observing the User Experience' is an accessible if not particularly comprehensive starting point; Vijay Kumar's 101 Design Methods is a broader look at the design process.