Short answer: don't choose an LLM API for a SaaS app from a public token-price table alone; replay a representative eval set through direct OpenAI, direct Claude API, and an OpenRouter-style routing path, then choose the smallest integration whose measured quality, billed usage, retry behavior, and recovery policy meet your release constraint. The cheapest path is workload-dependent. A low input rate can hide engineering overhead, while a chatty agent can turn one user action into several mod...