gpt5.4 pricing per million tokens is Input: $2.50 Cached input: $0.25 Output: $15.00
I tried re-running a rather long code review request I had lying around, and gptel says it spent 2.2k tokens; I don't know if that's input or output or what, but if we say it's output since that's the most expensive, then that single review cost me just $0.033.