These tools require API calls which usually aren’t priced like the consumer plans
Well technically Aider let's you use a web chat UI by generating some context and letting you paste back and forth.
Yeah they’re cheaper. I’ve written whole apps for $0.20 in API calls.
With which agent? What kind of apps?
Without more information I'm very skeptical that you had e.g. Claude Code create a whole app (so more than a simple script) with 20 cents. Unless it was able to one-shot it, but at that point you don't need an agent anyway.
I've "written" whole apps by going to GitHub, cloning a repo, right clicking, and renaming it to "MyApp." Impressed?