I purchased my coach in November, so am trying to find good resources myself.
As far as purchasing new raw fabric, that will be difficult I think. You might have more luck finding a couch in better condition than yours. firstname.lastname@example.org has surplus and used parts, but some web searching ought to find a Bounder being parted out (sold for parts). Of course shipping a whole couch may not be atractive, but perhaps the seller wouldn't mind removing the apolstry and just shipping the fabric?
Sorry I don't have more ideas,