The cost of a hot water boiler will vary depending on the size, capacity, and features that you need. However, you can expect to pay between $500 and $3,000 for a quality boiler. If you want a top of the line model with all the bells and whistles, you may have to pay closer to $5,000. But if you just need a basic model for your home, you can find one for as little as $500. Of course, the price will also depend on where you purchase the boiler and whether or not installation is included in the price.