No doubt that if you just wanted 1 sausage, you will need to buy the whole pack!
If they released the "R" version of the sausage, they would carry a massive premium with very limited availability...
By the time you find out the part number and come to order it, the sausage will have been superceded by an "improved Recipie" version, detoted with a "C" or "D" at the end of the part number -unless it follows the route of DV valves where the letter sequence makes no sense whatsover!!
Rich