Please accept the apology for the wildly left field suggestion here on a Porsche forum. The Manthey 996 is a very special beast and very rare. Can absolutely see the appeal. But it IS a lot of money.
If you have the time and are not in a rush, might I suggest an equally rare, just as sharp but dynamically more sophisticated alternative? See if you can speak to Bell and Colvill or Lotus Silverstone and have a go in an Evora GT430. They're outrageously good, and £60k less than the Manthey. If you can't have a go in a 430 (they're rather rare), either a Sport 410 or GT410 Sport will give you a pretty good flavour and there's plenty of those around (at £90k less than the Manthey).
Also appreciate this kind of purchase is at least as much made with heart as well as head, and the Evora might not float your boat in the heart department. But if you've not driven one, you really should. At the very least you'll have a laugh in the process (***** me, the 410s and up are good to drive) and know you made subsequently the right choice for you