I went in the other direction because their personal plan went from $5 (IIRC) to $20. I have a $5 droplet hosting it and the only difference is that I have to restart Ghost nightly or it will eventually seize up.
Honestly I don't know why I'm using it though. I probably should be using Jekyl or something like that.
I tried self-hosting Ghost for a few months, then decided I couldn't live with some of the lacks (at the time, you could not reasonably put it anywhere but at the docroot of a domain). It took me about a day to switch to Pelican, and I do recommend that in particular and static generation in general.
Figuring out what kind of workflow you want is crucial. A few additions to the Pelican makefile made things much smoother for me.
Did you try adding a swap partition? I'm using the ghost image from digital ocean on a 5$ instance and even when I set it up manually before I didn't have the problem you described.
I didn't, but I'm not sure my constitution will withstand setting up a swap partition for a system that could be replaced by make and a trivial HTTP server.
Honestly I don't know why I'm using it though. I probably should be using Jekyl or something like that.