I don’t know if this will help, but I can tell you that before my 911 center switched to a County run radio system, we had 7 transmitters that were each 100 watts a piece. They were all in one building/shed that had a separate electric meter. This meter powered the transmitters, Climate control and some lighting. That bill ran between $700 & $800 a month. Climate control was minimal and there was only one outside light that ran at night, the rest were on motion sensors while you were inside, which wasn’t very often. I only mention it so you can take into consideration utility costs in your figures.
We also had back up transmitters in other buildings, but they were rented spaces, so I never got a utility bill for them.