This has been a banner year for Roanoke Valley home sales. Realtors say historically low interest rates are driving demand at the very time when the number of homes on the market is also unusually low.  The average home sales price in the Roanoke Valley last month was about $266,000, up  about 12% from the year before, and the number of homes sold was up about 14%.  WFIR’s Evan Jones has more: