I've been to Mike's shop. My take was that for the time he has to put into re-creating those totally correct pieces, you're getting a pretty good deal!
Although any of the older Ferrari washer bags would look OK, the Lusso had a two hose cap on the bag. If a single hose cap and bag are available try it for looks. Tom Shaunassey usually has a few washer bags around. Jim Riff, Lusso 4537.