I have silk scarf "blanks" available. These feature "finished" rolled edges.
They are irridescent (they shimmer with a hint of a secondary color). This irridescence makes them more lustrous and interesting because of the secondary color that you pick up on as the scarf angle changes. These are 17 x 72 and cost $18. Once felted (well, obviously that depends on how much fiber you choose to use when laying it out), but generally when I use one of these I end up with a scarf that is about 8-9" x 55-60".
When I want longer or want to do a shawl, I use my hand-dyed silk fabrics (no finished edges, but that doesn't matter since you deal with these as you felt). I have various silks - organza, paj, chiffon, seersucker - by the yard. You'll have to call about that. It is either 45 or 54" wide and sold by the yard. We have so many colors and each is unique, so if you call and tell us a general color you're interested in, we can photograph the various versions in that hue that we have in stock and email you the photo so you can decide.
For instance, if you asked about something "grey" right now, we could send a photo showing a light grey (as you see on the outside ruffle of my Kiwi scarf below), a dark charcoal with shades of black, a medium steel grey with hints of plum and silver, and a dark black with highlights of grey. My hand-dyed silk fabric by the yard is $13.99/yd.