Have in-depth knowledge in your niche? Package it up into an ebook and sell it on your blog. I'd generally advise against selling it (at least exclusively) on Amazon or Kobo, as you'll probably be able to charge much less. If you've already built up a solid audience, you can probably change anywhere from $5 for a very short one, all the way up to $39+.
To all the bloggers out there…STOP sucking up to the very small, elite and narcissistic group of self-proclaimed influencers out there. If you all stop treating them like they’re special, they will not longer by special and therefore some of us who aren’t in there secret society will be seen as knowing what we’re talking about too! This isn’t High School, grow up and read someone else’s blog already!