House sellers\' asking prices are at the highest they have ever been for the month of March as confidence returns to the market, property search website Rightmove said Monday.  New sellers lifted their asking prices by 1.7% month-on-month to reach 239, 710 pounds on average, beating the previous record high for the month which was set in March 2008 by 55. pounds.  With asking prices also at 1.2% higher than they were a year ago, the spring boost should result in a sales pick-up in 2013, Rightmove said.  While the volume of new sellers coming to market has increased by 12% month-on-month, the amount of unsold homes has stayed broadly the same, suggesting that the number of properties for which sales are being agreed is growing.  The website, whose house price study has been running for more than a decade, found that the number of home-movers who believe that prices are set to increase this year is double those who believe it is set for a dip.  Almost one quarter (23%) of people moving house believe prices are set to edge higher, compared with 11% who are expecting decreases. The majority believe that prices will hold steady.  March\'s month-on-month increase was strongest in the South East of England, where prices lifted by 4.2% to reach 309,439 pounds.  While asking prices grew more slowly in London at 1.9% month-on-month, they are now 9% higher than they were a year ago, at 496,298 pounds.  Rightmove\'s findings add to evidence that the market is gathering momentum, with the Council of Mortgage Lenders (CML) reporting last week that mortgage lending to home buyers has got off to its best start to the year since 2008, analysts said.