Here the Power company handles all installation too the meter on the house. You pay them for doing it. With a step down transformer then 500mcm is more than enough. The service wire is sold in rolls with the correct number of wires spiraled up so that you pull the whole service wire off on roll instead of multiple rolls too get the required number of wires for the service and there is several different wire types that can alter the price. So you have too determine if you are pricing a single strand of 500mcm or 2 strands of 500mcm combined with a ground together.