IMO there is a couple issues you have to address.
First and foremost is finding the right RV for you. It must fit you and you have to like it.
Second is what you pay. I think you must pay a fair price. There are lots of stories about people beating the seller down but I think a lot of them are just stories. Yes there are some bargains out there such as estate sales but you have to keep looking.
It would be sad if you found the perfect unit and then because the seller got tired of dealing with you they decided to sell to someone else.
As long as you and the seller are happy with the price it has been a successful transaction. They are happy their unit has a reasonable value to someone else and you believe you have paid a fair price for a unit that fits you perfectly. You will be able to contact them for advice on the unit long after you have taken possession.
Gordon and Janet
Tour 42QD/inTech Stacker