Sotwell,
I dont llike desktops myself, but there is a need in the market place for this kind of valuation. I dont think banks should use them for actual mortgage loans funding. I do think they should use them to help the consumer decide on paying for a more complete typical mortgage lending residential report.
I dont know where your property is located, but in south Charlotte for example, $500K is not a custom home. It is a nice home, but not custom.
Gaston, Union and Cabarrus couties have seen significant across the board declines in market value since 2007. Higher end homes have suffered especially since the market for that price point is much smaller outside mecklenburg County.
The Waxhaw/Weddington area of Union county in the 400K + market has tanked. The higher you go in price point the worse it gets. There is not one specific reason in Union County why this has happened, but mortgae fraud enabled by frenzied buyers and low doc/no doc loans are the primary cause.
Gaston County to the East has a very small 400K market so values dropped quickly in the price point.
Cabarrus is better then Union or Gaston, but again, 400K price point market is small and demand is way down.
All lake properties are down significantly in Norman, Mtn Isle and Wiley.
Good luck to you.