What it actually costs to run a one-Rails-app SaaS per month

Founders coding with AI tend to land in the same place. The first version is a $200/month no-code stack: a page builder, a chatbot, an auth gate, a workflow tool, two or three other SaaS seats glued together. The second version is a Rails app on a single host that costs $40/month. The transition keeps coming up in client conversations, and the math changes the day you decide to rebuild. Most online answers about what that math actually is are partial. Hosting articles list the host's monthly fe...