I notice that the sump plug washers on my 156 is a bit stuffed, so i looked up ebay, and they were about 3 pound plus one pound delivery to Australia, i thought this is a bit steep, and i know these are also called DOWTY washers or BONDED washers, and i purchased some from a bearing supply place for about $2.60 each, just don't tell them they are for an Alfa, Colin.
Hey ColCol, awesome tip! If you mentioned anything about an Italian car, they surely would have doubled in price!
From my recollection I think the genuine ones were only about $5 but convenience is a big factor so I'll have to see if there is a nearby 'bearing supply place'.