You should ask initially for a cost breakdown, for the tracking & connections. If you ask them for the spec for cable depths, you could dig the track, lay cable/warning tape & backfill, and get the power company to do the connections.
I am currently getting charged £670 to connect up 1 lighting column in Cumbria, they have a monopoly but there is nothing stopping you in completing some works yourself. One major issue in price rises is the cost of copper for the cabling.