In the first article in this series, we landed on a mental model that cuts through most of the confusion about AI: a large language model is a language processor. It takes language in and gives you transformed language back, the way a food processor takes in vegetables and hands you back something chopped or blended to spec.

That framing answers what the tool is for. This article answers a question that arrives the moment you start using it for real work: what does it cost to run, and how do I tell a good deal from a bad one?