The groups are still on line. Members do post lists of scarves for sale periodically. You need to email the moderators for an invitation to join each group.
London and Paris both have resale shops which sometimes have scarves. Quaility varies enormounsly. Check things like the "Time Out" shopping directories for each city, or do an online search for newspaper articles / reviews.
I echo what others have said about its-all-goode. Jan is highly reputable and expert in all manner of Hermes textiles. She is great on either the sell or buy side, and a very nice person as well.
Very helpful seller. Excellent selection of scarves, very accurate descriptions, and lots of education to boot. Quick to direct you to another seller, like greenjade, designer silk scarves, and luxury-scarves, when she knows they have something that might suit you.