When I bought my Lexus years ago, the finance manager try to sell me the paint sealant for $800. After I refuse repeatedly, he lower it to $600 and then $400, I turn it down. A few weeks later, I was at a detail shop and I ask the tech how much he would charge for the same type of paint sealant the dealer was offering, he said probably about $100. The dealer's profit margin on these add on are outrageous. Back then, the paint sealants are made from Teflon which did not last very long. The newest technology is polymer which is much better:
http://www.autogeek.net/optimum-wax....FcZQ7AodUFQAWw
If you do decide to get the paint sealant, make sure the product is polymer based.