You're right- there doesn't seem to be a retail source. I did see some hits for "PVC leather" while looking for Clarino, but the links seem to be for finished products like jackets and handbags.
Try
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Type "suede" in the search box or try browsing thru upholstery fabrics- there were some polyester suedes in there. I don't see "Clarino", but maybe one of these is a reasonable facsimile? I work near the Fabric Place in Randolph, Mass and could pick up some samples for you. How big of a piece of Clarino do you need? I might be able to cut off the knee patches from my daughter's outgrown riding pants. MM