I have very good audio and video engineering skills. I've built several
recording studios, radio studios, television studios, PA setups, etc.

I was just asked to become the as-needed engineer for a semi-pro
baseball team. I've never done a baseball stadium, but how hard can it
be? They have an announcer booth with several mics, mixer, SFX/music
from a computer, and a centerfield video screen fed by another computer
and an ENG camera feeding back by microwave. I think I can handle it,
but how much should I charge per hour?

I'm thinking $25.00, but am I low-balling it too much?