Token estimates are only one line in an agent budget. A realistic plan also counts platform subscriptions, integration limits, setup labor, monitoring, retries, storage, and the human minutes needed for exceptions. The cheapest model can become expensive when weak reliability creates repeated review. A Blueprint should therefore state a normal monthly range, a stress case, and the event that stops or narrows the workflow. Start with a low-volume acceptance test and measure real runs before committing to subscriptions or a larger architecture.