How much to rewire a 1200 sq ft home?

There is no way to price this without knowing a whole lot more about your situation. Call at least 3 electricians and get quotes. If you are re-wiring there is a reason and that reason alone can affect the cost. For example, do you need a new main panel, are you increasing service from the power company, what kinds of walls do you have, is the house 1 or 2 floors, is there an open ceiling basement, do you have a number of dedicated circuits, do your fixtures and receptacles and switches need to be replaced and so forth.