At that point I hadn't thought about selling it, I just wanted to quickly finish it and release it. I'd thought about it originally, an extra revenue stream is always welcome, though I wasn't sure if the add-on might be too simple for the Blender Market, but all that slipped from my mind until I was a few weeks away from releasing it for free. Reminded of my idea to sell it I did a bit of investigation and applied to be a vendor on the Blender Market by describing the product I would like to sell. My application was approved, which meant I had to fill some of the extra requirements of releasing on the Blender Market. Don't get me wrong, they're perfectly acceptable requirements, ones I would have set myself, just ones I hadn't been thinking of when I thought I'd "quickly finish and release it". I wasn't just finishing up the code, I now had to think about a video demo, documentation, product images and descriptions, future updates and promotion. I was reminded of each one of these just at the point I thought I might be nearing the end. So the project, like all projects, was a bit longer to finish than expected.
There is also a bit more pressure when releasing a paid add-on. Getting it functional wasn't good enough, I now had to look at it from the perspective that someone would be buying this and expecting it to work in a professional way. People might be using this in their workflows. What if it crashed and they lost their work? Suddenly, things that I thought were fine for a free release stuck out as dysfunctional. Things that I knew had to be in place for tracking to work had to be checked for and the user warned if they were missing. Every circumstance a user might get into needed to be accounted for. The add-on requires a camera present in the scene. What if they delete the camera? What if they manually turn off settings the add-on has turned on so it can work? What if they're idiots start pouring pasta sauce over their keyboards because I've accidentally pasted a lasagna recipe into the documentation!?*
The days after the release were spent answering questions from all the various places I'd posted it, solving bugs and talking about future features. I hadn't quite anticipated the amount of attention it would need after the release, though I was aware that part of the Blender Market commitment is that authors provide support for products. Luckily, it seems to have settled down now and I have received a modest, but pleasing amount of sales so far. This coming week I hope to be able to return to my modelling projects and improve the add-on steadily over the next few weeks and months.
*I will not be held liable for any damages incurred by pasta sauce or any other ingredients which when combined could constitute a 'lasagna'.