How much does it cost to add a fireplace?

In March 2011, Washington state, cost to add a gas fireplace and standard size/quality unit, including construction costs and Plumbing gas lines where service already exists: about $5,000.

Could cut costs to as little as $3,500-$4,000 by going with a very inefficient smaller unit, but if you're spending money on natural gas you might as well actually put the heat "in" your home rather than outside by getting an efficient model.