I only know Yahoo but I think there are others. http://yahoo.aleado.com/search?query=b16b+エンジン&item_status=2&page=2
Though you will probably need to find a local agent to get it shipped to Switzerland. Getting an engine from Japan won't be cheap but depending on how much in a hurry you are might be the only viable option, it took me two years to find a truly healthy B16B and that still had 70k miles on it.