They are trying to rip you off. You need to do the research from one IP address, or maybe computer (don't know if it was MAC address specific) and book from another. I noticed this on airbnb when booking in Europe. It must be something that is landlord specific (for airbnb anyway), because not all properties did it, but one in Venice went from $420 to $609 in the course of my deliberations. Which was good, because we found a nicer property for less than $420.
I noticed it on air fares too. The bastards are out there, and they are out to get you!
