Welcome.
The Gran Cabrio, now you don't see many so we have to assume they did not sell that well, so this should be reflected in the price.
The sun is out so its an expensive time to buy any convertible but it is well know the main dealers have loads on their books that they are struggling to shift.
If it were me I would go to someone like Dick Lovetts with a clear budget in mind and stick to it. I think you will be amazed what you come away with.
As for white, I love it and if your brave enough, couple it with the red leather interior, superb!
What I have heard is there have been some hood issues both with the mechanism and leaks so get them to pressure wash it with you in it and check for leaks.
Remember there is a new model out now with the face lift (I think its referred to as the Stradale) so this will have a direct effect on the value of the older model and the dealers will be biting your hand off to shift them.
Good luck and let us know how you get on.