An appraisal is a professional estimate of a property's market value, based on recent sales of comparable properties, location, square footage and construction quality. This service varies in cost depending on the price of the home. On average, an appraisal costs about $300 for a $250,000 house.

A comparative market analysis is an informal estimate of market value performed by a real estate agent based on similar sales and property attributes. Most agents offer free analyses in the hopes of winning your business.

You also can get a comparable sales report for a fee from private companies that specialize in real estate data. You also can find comparable sales information available on various real estate Internet sites.