To answer one of your questions... From the registration page: "Your credit card will be charged a fee of $24.99 to complete the registration process."
If we could find another way to keep the signal-to-noise ratio high, I would love to offer this service at a lower price point.
Awesome job, by the way.
It seems lowering the price would gut your revenue but you wouldn't increase your userbase enough to make up for it (there would be a big deadweight loss of utility that patients get, but don't have to pay for -- lost revenue for you).
Also, ER is an incredibly expensive thing to go through, so mentally your users may be more price-insensitive than usual--they'll bucket all the costs together in a 'big bath', so you can charge more.