I have one extra one of these RSRacing hub-extenders... 100 bucks plus shipping.
It acts as an adapter as well - it has bolt-patterns for Momo, Sparco, OMP etc on the one side of it and then the matching bolt-pattern for the standard Alfa hub on the other side of it...
The nice part is that it pushes the wheel out towards the driver and helps to rid the car of the machismo-Latino - arms extended - driving style...