2006 rockwood travel trailers

My wife and I have been looking at new 2006 Rockwood Trailers. The price posted was $18,000. Is buying trailers like buying cars? Do you pay posted prices or do you negotiate? I was given a price of $19,500, this is tax title and license. This also included an equallizer kit, friction sway control, and brakes installed. I am looking for advice if this is a good offer or do you look to pay a certain percentage of the asking price?

Thanks for any help,