A lot of Maine homeowners might be surprised to learn the market value of their real estate.

During the three-month period ending Sept. 30, the median sales price of houses in the state was $162,000, which represented a 13.3 percent gain over last year’s price of $143,000.

These figures were compiled by the Maine Real Estate Information System and were based on 4,127 sales recorded by the statewide Multiple Listing Service. The median price indicates that half of the houses sold below that price and half sold above that price.

Coastal real estate has had a pricey reputation for a long time, but the current increases are being shared by most areas of the state. In Penobscot County, the median price increased about 15.7 percent to $115,000. Jon Dawson of ERA Dawson Bradford Co., a Bangor real estate agency, said the typical price in Greater Bangor, at about $130,000, is higher than the Penobscot County figure.

Coastal real estate is still registering huge gains. Prices in Hancock County increased 26.5 percent to a median of more than $177,000. Jim Paulas of Saltmeadow Properties in Blue Hill said demand has pushed coastal prices higher for a long time, but since the stock market woes started a few years ago, demand has increased even more. The reason, Paulas says, is that people with some money see coastal real estate as a better investment than the stock market.

And like every other area, coastal demand has been helped by the low interest rates that have made all homes more affordable.

Demand has been so strong that Paulas’ company has struggled to keep an inventory of houses for sale. He says his inventory is probably about 60 percent less than it was a few years ago.

Pam Coffey Paine, who sells real estate for ERA Dawson Bradford, said one reason for the gains in Bangor was the increase in upscale homes being built by prosperous people moving to the area.

Paine said doctors and others moving to the area come expecting neighborhoods of pricey homes. In Maine, neighborhoods are often made up of homes with all kinds of price tags intermingled.

Paine said some of the new arrivals, not liking what they see, rent for a while and then build an expensive home on land of their choosing. These homes are readily evident in the Bangor area. It’s not uncommon to see huge colonials with three-bay garages, three-story foyers and other fancy features.

“Just a few years ago a $100,000 home was expensive here,” Paine said. “Now you can’t get a lot for that price.”

Paine said Bangor wasn’t yet as expensive as Portland, “but we’re moving up fast.”

Historically, mostly rural and relatively low-income Maine has seen housing prices well below the national average. This is no longer the case. The median price nationally was $172,300 in September, or only about $10,000 higher than Maine.