You could use a freemium model where registration and tracking the first two candidates is free, then you have to sign up. You should also try to contact other

You could use a freemium model where registration and tracking the first two candidates is free, then you have to sign up. You should also try to contact other HNers who were active in this space, there may be an industry related catch you don't know about. I did this regarding a freelancer site idea, and learned interesting facts. And use a service like pickfu.com to test as much of your idea against real people as possible before writing a single LOC =) I tried this with my project idea, and it was interesting.