Comparative Market Analysis, typically done free of charge. They will use factual sales from the past 6 months that match the criteria of your home. Location and style drive the value immensely, so use a professional to help.
Always select your Realtor before searching for your new home. Your best research and advice will come from them, years of experience and knowledge of current trends. I suggest getting a Market Analysis for your current home and then listing it. Only then will you know what price range in your search is realistic.