It was arround 220 Euros when I bought it 2 years ago.
He custom build a 235/6 cylinder/6 Volt version for me.
It was usualy thought for the Citroen 2cv (4 Banger).
Since the guy is retired it is more a hobby for him and his Citroen 2CV friends than a buissines so I think the price will be the same, but you can drop him a line, he speaks englisch.
Here is his adress;
[email protected]Frank