I think it's going to be hard to build an audience with a paid newsletter from the start. It seems like you should write for free + Patreon. As you build your email list and audience you can then start including non-intrusive ads or your own offers, for example an ebook. Eventually once your audience is large enough, you can add a premium list and convert your existing, already highly targeted audience.

Nathan Barry has a book called Authority which basically talks about this.