Shameless plug: I know this plug should not be here but I think I can help some people with cost problem via (the easiest automation platform for AWS)[1].

I have a startup plan where you can run 60 executions in a month free of cost. Just reach out to me via https://totalcloud.io/solutions.html and refer YComb.

[1]: https://totalcloud.io

I have been thinking about something similar but stuck on a different project. Great work!