This is from STD Canada (see email below from one of their rep). Their Head Office might be in US but I am not sure if it's available in Europe. Note prices are in Cdn $$. I just noticed they have a section in Facebook and I saw a Cayenne using this suspension.
"Price for the R1 (Height adjustable, dampening adjustable, pre-load adjustable)
Price for the R3 (R1 + front pillow ball upper mount + adjustable camber)
Booth are in stock in our Canadian Warehouse, price are in CAD, free shipping, no hidden fees, no duty fees.
At your door in 24 to 48 hours.
Std Standard Canada