It's going to depend on additional upgrades and lot premium they may have added to that particular home. In areas like Positano and La Villita, a BPO (broker's price opinion), or CMA would be the best way to determine market value. The tax records there tend to be out of whack. I was just blogging on Irving and Positano the other day. Check it out.
Let me know if I can be of further assistance.
Me and my wife rent villa furore a woderul Villa for a week for next june 2010
You agent can get you all these answers
Let me know if you need any help.