Vintage Manual Sony Discs - Source needed

[Mike Davis]

I'm looking for a source for vintage Sony 3.5" discs.  I'm specifically 
looking for the old manual operated shutters.  Those were the ones 
where you had to open the shutter manually and then squeeze the 
corner to get it to snap back.

This is not a case of simply finding something to work.  I'm specifically 
interested in those vintage discs.

If you don't know what I mean, go here for a photo.
http://www.msdsite.com/forums/showthread.php?s=&threadid=1647

I have a dual disc drive that uses these and I'd like to keep it as original 
as possible, including using original discs.

Thanks,

Mike