I've been in touch with that seller, having acquired several Twiggy disks that he recently offered. He has several Paul Baker items that have not yet been listed, too.
Regarding these disks, I went through the Apple software that he's offering and haven't seen anything that's hard to find. The Workshop supplements, etc. are available in the Apple Technical Information Source CDs - which is actually why I posted that thread earlier today. What am I missing? What's special about the disks from the seller?