The average list price for a four-bedroom, two-bathroom house in Boulder has tipped the $1 million mark, a fact that places the Boulder among the most expensive housing markets in the country, according to a new survey from Coldwell Banker. Of the 2,722 areas surveyed, Boulder ranked 27th with an average list price in the first half of the year of $1,044,656. That places Boulder in the top 1 percent, not counting resort areas such as Vail and Aspen, which were not included in the ranking. (Last year, the average list price for Boulder was $835,516.)