So if it were me.
I would call the electrician. Find out the best way to handle it. Then i would see if i could shave their labor down by doing the grunt work. No reason to pay them to trench wire from the house to the dock and run conduit down it. Leave it all stubbed out where they tell you to put it, then pay them to come and land your pedestal\wire transformers\hook it to the house.
You save money doing the idiot work, but still get an electrician hooking it up safely and doing all the maths.
The cost of wire vs the cost of transformers is just going to come down to how much power you want.