As you get more experience with vacation rentals, I think you'll discover this is the norm (and fairly reasonable). Until you commit to renting a place, the owner has to assume you are looking at multiple properties and may or may not ultimately choose his. In Windsor Hills, owners often receive 10+ inquiries daily and a very small fraction of them end up renting. The one caveat I would make for myself is that if I have been going back and forth with a potential renter and they seem very serious, if they were talking to me first, I would typically send them a quick e-mail saying I need a commitment now or I'm going to have to go with the party that is ready to commit.