The answer to 'how much to fix heat exchanger in my area' is that the cost to repair or replace a heat exchanger can vary significantly depending on several factors. The typical range for heat exchanger repair or replacement is generally between $500 to $2,500, but the exact price will depend on your specific location, the make and model of your HVAC system, the extent of the damage, and the labor costs in your area.
The heat exchanger is a critical component of your furnace, and it's important to have it inspected and repaired by a licensed HVAC technician as soon as possible if you suspect an issue. Attempting to DIY a heat exchanger repair can be dangerous and may void your warranty, so it's best to leave this work to the professionals.