We started out charging people $10/month for our service, and most of our users felt that was a fair price. We are playing with some other options now. In the healthcare industry there are a lot of possible payment models.

We have done a lot of internal calculations to prove that we can make the numbers work, but you are right that covering the costs is a challenge for this type of service. Without revealing too much, I'll say that part of our secret sauce is the way that we provide high-quality feedback at an affordable cost.