The average cost of a well pressure tank is $200 to $800 for the unit itself, assuming you outfit your well system with a 20- to 80-gallon tank. Smaller tanks may cost as little as $50 to $100 ...

We paid $570 (electric) and $600 (gas) for the two 50-gallon Rheem tank water heaters we tested, but we have seen tank water heaters priced for less at home improvement stores.