Now isn't the time to worry about price because you are not sure you want it until after the inspection. As it is I would be checking around to see just how much the batteries and tires are going to be.
Now I'm willing to bet that it's the dealership rather than the owner being inflexible. Saying that it is the owner is a easy cop out that can't be argued. You have already shown a great deal of interest in the rig and even put money down, they have little incentive to give in. Pull your money and walk away and they may change their mind.
If this is the rig for you and they wont come down, you may go at it from a different angle. See what kind of deal they can get you on what the rig needs. (after checking around of course)
