Someone emailed me a couple hours ago off this thread and I'll share here what I replied with. I've removed client names because, well, go get your own clients.

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Yessir, happy to share. Here are some pieces we have written in the last couple of years that commanded at least $500 per. I will trust your HN'honor to try not to poach or anything, and it wouldn't work anyway.

(redacted)

Many people (including many who post on HN) think "That doesn't seem so special. I could do that." But that misses the point. As I mentioned in the post it takes TIME to write something of quality that people want to read. The internet is full of bad blog posts so companies are looking for quality writing that has a point of view. If you imagine that a proper blog post would take approx 4 hours to research, draft, edit, review then the company/customer has to decide whether to allocate a $60k/year full time employee to writing it (which would be approx $120 of salary) or they can farm it out and put that employee on something with more measurable ROI like PPC management.

Organizations know they need blog posts and those that (1) have a good revenue footprint and (2) sell to the enterprise view blogs differently: it isn't always about getting a new lead and SEO. It's also about VALIDATING a decision a prospect is already thinking of making when they come to the site. The piece for (redacted) above wasn't about getting new leads or SEO juice or shares. It was specifically written to help them close a deal with a large TV studio that wanted to make sure their web partner was led by honest enthusiasts and not some anonymous ownership group. We turned it around in 2 days so they could get it in front of the prospective client before a decision on the RFP was made. We wrote that post while they were in a competitive situation against a much larger firm (Leo Burnett), a firm that has amazing work didn't know how to display the same "human" personality. (Our client) won the 6 figure deal. The money they paid us for the post was customer acquisition cost no different than having taken the prospect to a fancy dinner.

If you want a roadmap:
Find companies b/w 10 and 50M in revenue
Find those that are publishing blog posts irregularly or not at all. Irregular means they are doing it themselves without much structure. Not at all means they aren't doing it at all. If they are posting on the same day each week or every other week then someone has beaten you to the punch; move on.
Reach out with a HIGHLY customized email message and offer to write one post at no charge. This is your "offer they can't refuse."
The post is their's to use however they like even if they don't pay you. Ask, however, that if they do like it that they spend 15 minutes on a call so you can hear their ideas if they had unlimited blogging capacity and then share how you might be the person to fill that need.

From there we usually get people into a blog services contract of $1,000/month for a post b/w 700 and 1000 words 4x a month. If they want us to do the content map, post more, come up with the post ideas, fast turnaround, etc. then the price goes up. We have a number of $2,500/month contracts that include us doing the calendar along with the subjects/strategy, 4x blog posts, and 1x longform (eBook or whitepaper). I farm the work out for approx 40% of what we charge the client.

It's not a very difficult sell. Good luck.