I paid a company $45/month to maintain my FW
tank at my office. They charged $75/ month for saltwater. It included two visits, about 5-10 min, water change, food refilled in auto feeder, included all food, filters (I had a fluvial canister so they didn't do anything to it at every visit). They would even bring me fish if I wanted different ones. Their saltwater program was similar, it was more if you wanted to rent their tank and fish, $125/month.
I'm in Ohio, that is about what I considered a good price to pay someone so I didn't have to do it. So about 20 min/work/month for $45. They timed mine with a business in town so they only made one trip in our direction.