I get that people are frustrated with heroku's pricing, but at the end of the day I think that if your side project isn't worth the money you spend on it's hosting, maybe you should look into other side projects? If it's truly not a money-making project, not needing to scale it or have it up 24/7 seems like a reasonable trade-off to not paying for it's hosting.
The number of tools and resources Heroku provides is quite significant, and developing/deploying/maintaining similar solutions is certainly not cheap or easy. Especially at scale.
Disclaimer: I'm one of the Dokku maintainers.
- [1] http://progrium.viewdocs.io/dokku/
- [2] http://convox.com/