Question about cost to rewire a car

Do it yourself most kits all wires marked get one that has extra circuits in it so you can add to it if you want. Power seats power windows seat ejector auto machine guns and oil slick. Or other useful stuff. It is pretty simple to do. After I got a price I figured I could screw it up 3 times and still be ahead. Plus you will not have to figure out what someone else did.