What drives the price
The unit itself is usually only 40–50% of the bill. Labor, permit, new shutoff valve, expansion tank, and disposal of the old unit make up the rest.
Attic and crawlspace installs cost more than a garage. Switching fuel types, moving the location, or upgrading from 40 to 75 gallons means new gas line, venting, or a 240V circuit — each adds $500–$2,000.
Repair or replace
A thermocouple, heating element, or thermostat is a $150–$400 repair and worth doing on a unit under 8 years old.
Rusty water, a rumbling tank, or any water on the floor around the base means the tank itself is failing. Tanks do not get repaired — replace before it lets go.
Before you sign
Confirm the quote includes the permit and inspection, a new expansion tank where code requires it, and haul-away. Ask for the model number so you can check the warranty length yourself.