There's plenty of long answers about plenty of different things that can be done.

You want a one word answer: www.ontraport.com

A solid entry level marketing automation platform will allow you to segment your database and regularly email people with relevant and interesting content you can pull straight from your blog.

If you're already doing the writing, it won't add much work to your marketing load and got $600 a month you've got a good starting point for being much more responsive to your database and being able to engage with them much more regularly.

Oh, and with the next $80 sign up for www.oktopost.com to get smart about your social media marketing.

Now you've got some great marketing going on and you've still got $320 to find yourself some awesome advice on clarity :)