the 456 estate was specially bulit for the sultan of Brunei, all of them were for him, he has a huge car collection, he first approached Ferrari but they refused to make an estate, so he went to the next best place, Pininfarina, who as you all know design all the modern day ferraris, including the 456 GT. the project did cost a lot of money, but that was something he was not short of in those days.
There have been 2 that I know of for sale in the UK, sold by I believe, Taylor and Crawley, London. who often get very rare cars to sell.
bnr34vspec2,
Benneton F1 team a few years ago, transfered the engine out of Michael Schumacher's benneton F1 car and put it in a Renault Espace people carrier, making it Renault Espace F1, a grand prix car with he body of the Espace, very rapid. so as you said, money no problem, anything is possible.