Something is not quite right. The OP did not provide the year, make and model of his vehicle - but did post in the 3rd generation forum. I checked on a price for the OEM positive battery cable for my 2015 Ford Expedition Limited 4x4. The Ford list price was $465.89, with an available purchase price of $279.73. I know this is expensive - but not the $550 that the OP stated (plus labor). Ford also issued a TSB with Information on how to replace the terminal wiring connector, and not the entire wiring harness. The OEM connector is very inexpensive, and a good alternative to replacing the harness.