I paid about $1500 for my headgasket at a local dealer. I own a '98 Outback with 108K miles. The price included a new timing belt and spark plugs.
An independent shop wanted $2200 for the job. That included machining the heads, but did not include a new timing belt. I decided not to work them because of the price and the fact that I had already given them $150 to mis-diagose the problem i the first time.
From my unerstanding, the DOHC engines cost more than a normal car because they have two heads. I could be wrong about that.