I absolutely hate the part where the sales person tries to flog you an 'extra'. I know they have to do what they can to make a commission and I know it's up to the individual to say yes or no, but it gets on my wick tbh.
Glad I bought our own 500 from an independent. He didn't try to flog me anything other than GAP, but as previously posted, he got ultra short shrift from me and that conversation lasted less than 20 seconds. Nope, we walked away with an almost brand new car for a fantastic price (without Supaguard by the way!), deal done in an hour.
With our MX5 when we bought that new, they tried to flog us Supaguard. "Don't push your luck" I believe was my reply. Personally, as already posted, I'd save your money and spend it on something else, but it is your choice at the end of the day.