This is a really interesting product - I can see how it would be useful to a wide audience. However IMO I think you may be pricing a lot of customers out of using your product. I developed a scheduling / booking app (
http://www.meetingshed.com), and I found I had to offer a free tier to drive users to actually register and try out it out. Hope it works out for you though. I'm sure HN folks would be interested in learning about the user demographic and how the business develops.