So. I immediately upgraded to the Black Hat plan (no ads forever) and would say you are charging way too little or should not use in app purchase.
We HN users are a dedicated base of people. While you need data to decide this, I think you will find that most people will pay more than $3.99 for no ads. I think most of us are happy to pay for a quality product.
Outside that, I really hope that this will become my go-to for hacker news :)
Caveat: for some reason I cannot post a comment from the client but the error is not verbose. It also says "tu " instead of "to". Just a note.