Many things affect the final price. The size of your new water heater matters. Bigger tanks often cost more. The brand you pick also plays a part. Labor rates for plumbers change by area. How complex the job is also adds to the cost. For example, moving the water heater's spot can make the job bigger.
It is smart to plan ahead. Get quotes from a few local pros. Ask about all parts of the job. This includes the new unit and installation. Also ask if permits are needed. A good plan helps you budget well.