The best time to be getting all these toys is when you buy the car. Ask yourself if you want these toys. If you think you do, then go buy a fully loaded XLS (like I did), and haggle the dealer to death. Aftersales is NOT a good idea to be adding these OEM options, because you will pay a lot, because then you will need to have the dealer kill you for the price of the part, and kill you again for installation, which you would want them to do it if you want warranty. I got quite a bargain with my 07, and the Navi with Luxury option almost came down to 0$ after some haggling, and since they came preinstalled at the factory, I have full 5 year warranty on all these options, and I don't have to pay shipping and installation, plus I got a huge discount so they almost cost free.

But.... that's all water under the bridge now. More like an advice for future buyers.