Municipal sign installation is a decent floor approximation. Can run into the thousands if it's electrified (think: blinking lights on a warning sign). Depends

Municipal sign installation is a decent floor approximation. Can run into the thousands if it's electrified (think: blinking lights on a warning sign). Depends on availability of electricity, engineering, weather at that time, etc. In some places, a stop sign can be close to $2,000 based on some quick googling, and that has no power supply to worry about. It's always more expensive than residential bc it's publicly reachable by a million morons, and is meant to stand much longer than residential work.