I’m having a similar internal debate myself - it all boils down to what is most important to you, and what the pros and cons of each approach are.
If you go for the self-hosted option via Digital Ocean, you can be up and running within minutes, and at $5 a month, it’s a lot less than the cheapest option available on Ghost Pro. But in doing that, you’re taking on a lot of responsibility, and if anything goes wrong, it’ll be your job to fix it.
Going for Ghost Pro, on the other hand, will cost you more, but has an even quicker set-up than being self hosted, has a guarantee that it’ll work (and if it doesn’t, you get to shout at someone else to fix it for you), along with extra nice features such as a free CDN, etc… - but you lose out on flexibility (such as the ability to use custom plugins, etc…)
If you want to learn what it’s like its like being a devops, and to gain experience in fixing problems that might arrive, go for the self-hosted option - after all, learning how to set-up your own CDN might be fun - if, however, you just want something that works, go for Ghost Pro.
(Alternatively, why not look at something like Jekyll with free hosting on GitHub Pages?)