Ratchet Back Rest info needed


I am looking for info on where to get ratchet back rests from? I don't want the back rest itself but just the ratchets and straps. I am trying to use them in my C1 but the ones that came with the boat are too short and I need longer ones. So does any one know where to get them from? My local ski and board shops don't want to know about it till winter when they have all there snow gear but I want them now. Any help would be great.
Thanks Wayne.