Back in the 80s I worked on a few underground projects that included water mains and power lines through towns, out in the country, and in new subdivisions. This was all over Central California. Because of earthquakes, and rocky soil, the requirement was for at least a foot of sand to be all around anything buried in the ground. Most trenches where 3 feet wide, and the hardest part of the job was getting the sand in the ditch all leveled off for the pipes. I never saw anybody pull wire through the conduit, so I don't know how involved that was, I was just there for the installing of the pipe/conduit, and then filling in the trenches. Knowing how many people where involved in these jobs, and what it costs to move equipment to those locations, and how ridiculous insurance was back then, I would think that going overhead would be a lot cheaper then underground. Something to consider is how big the conduit has to be for high voltage. Not the service line to the building after the meter, but the line going to the transformer, where the voltage is reduced.
When I ran power to my place 20 years ago, I was told to provide a list of how much "load" I was going to use. The more power I was going to use, the lower the cost for the install. My line was close to 2,000 feet. It crossed a State Highway, and then came down the Highway before entering my land. My neighbor allowed the power line to run inside his property line, so there wasn't any issues with the Highway officials.
Because I put in a 1,200 amp meter, they did all of it for free. I had to pay for the breaker box, which holds six 200 amp breakers. It had to be mounted on a concrete pad, which I did myself. I hired an electrician to connect the meter to the breaker box, which was around $200 for about two hours of work. After the breaker box, I did everything myself with direct bury lines to my buildings.
In my experience, asking the Power Company for the best way to do this is what saved me a bunch of money. They where very helpful, and went out of their way to work with me. As a remodel contractor, I've had a few dealings with 3 different electric utilities in my area, including a co-op. In every case, they have all been very helpful at getting new power to where it was needed. The client would make the phone call, somebody would come out, we would all get together and talk about what was needed, and they guy from the power company would put together a plan to make it happen. We just let them do their thing, their way.
The one time that I had a problem that was at my place, I had to contact the State Commission to get it resolved. I forget who that was, but once I contacted them, it was taken care of quickly.
If you are struggling to get anything done, I would consider contacting the government agency that overseas the power company in your area. Not to complain, or cause trouble, but to ask for help and guidance. It can't hurt, and sometimes you might be surprised at what you find out.
