Creating an account, building the listing, and saving it as a private draft costs nothing. Nothing is published and no one is charged while you refine your positioning, asking price, or buyer brief.
Publishing requires an active listing subscription: $29 for the first month, then $39/month until canceled, plus any applicable taxes. The subscription is what puts the listing in front of buyers, so make the evidence complete before you start it: a clear product story, honest metrics, screenshots, included assets, and a transfer plan.