the cost of redoing electrical wiring

Okay, you are asking two questions. So I will give you two answers:

1. The electrical work- This project may seem very straight forward, but actually involves multiple variables and components. My company routinely performs this type of project so allow me to give a brief explanation of what is involved. For the sake of this explanation, I will assume that when you say "redo" you mean rewire the home.  This project must be performed by a licensed electrician, and a very good one. Many of the guys who have made their money doing new construction electrical work will not want this job. The electrician must pull a permit with your city, county, or municipality.  This required because of the complexity of the job as well as the inherent risk associated with the work. When my company performs this type of project we replace everything attached to the house, unless a partial service upgrade is requested. That means the service main, weather head, meter base, and breaker panel box.

Before price shopping a job it is important to realize what work will be involved to complete the project. And when I say complete, I mean to return your home to the condition that it was in prior to the work. Electrical rewires almost always involve cutting sheetrock to run the new wiring. The layout and installation of the existing electrical work, as well as your budget will dictate how much cutting takes place. With that being said, it is possible to run new electrical with very minimal cutting. However, it will increase the cost of the job because it will take the electrician more time to fish the wires through walls floors and ceilings, than it does to cut the sheetrock.

Before beginning your project it is important to do any environmental testing that may be deemed necessary in your area. The big two are lead and asbestos.

Now assuming that your tests come back negative, and the electrician runs all of the new electrical work and the work passes rough inspection, it will be time to close the walls back up. Now this is the part that you may not have been ready for. If you are lucky, the electrician used a sheetrock knife and made precision cuts removing sheetrock in pieces that can be reinstalled, but in most instances this will not be the case. There is a good chance that you will at least have one whole under each wall outlet in the house. So now you need a tradesperson that can patch and finish sheetrock. Once the sheetrock has been patched and refinished it will need to be repainted to match the walls. If you have rooms with wallpaper it may be worth it to have the electrician try to fish the wires without making cuts. If you have chosen only to replace the panel the work can stop here.

However, if you are replacing your weatherhead, and your weatherhead goes through the roof, you will also need a tradesperson to perform a roof repair to the area where your service conduit enters the home and install a new rubber boot to keep water from entering your roof at the service penetration. If you plan to replace the meter base you will want your electrician to confirm the location of the new meter base with the electrical inspector. In my region, the electrical inspection department requires the relocation of the meter base from the rear of the home to the side or front. In some cases the meter base is installed near a driveway or under a carport. In these instances bollards may have to be installed in front of the meter base to prevent vehicles from hitting them. I think this covers the basics of the job. I will shy away from giving a price because I don't know your market. You also have to decide if you want to replace your existing light fixtures. Once everything is buttoned up it will be time for the final electrical inspection. My advice is to make a list, set a budget, and then get prices from contractors.

2. The master bathroom addition cannot be priced without details on location and specification on design and finishes. Even with that information an in-person site visit would be required.