How I Built a Production AI Agent for $5/month Using Open Source + OpenRouter Stop overpaying for AI APIs — here's what serious builders do instead. I spent three months running an AI agent on Claude 3.5 Sonnet through OpenAI's API. The monthly bill hit $847. Then I rebuilt it using open-source components and OpenRouter. Same performance. $5.23/month. This isn't a theoretical exercise. This agen