For the reasons stated above I also recommend you DIY. If you don't have the time, and cost is no object (it's amazing how a small job can turn into a huge bill at any boatyard), I've always been impressed with Lunde Marine Electronics in Ballard. I don't know if they do basic wiring, but I know they do electronic installation. Very knowledgeable and excellent customer service. I have gotten advice from them and bought some things however I have not had them install,
repair, etc.