Some very good answers here. But two things should be noted. First, countywide and even citywide prices do not tell you what prices are doing in particular neighborhoods, and neighborhood prices do not tell you exactly what to expect of a particular house. Second price trends do not always reflect what houses in a specific price range will do. Sometimes average and median prices rise because more people are buying expensive houses. Other times, they fall because there are more entry-level and downsizing buyers.
In other words, the numbers tell only part of the story.
Prudential Real Estate of the Rockies