I'm not sure there were that many. Certainly when I joined Emerald the company paid for the rating. (Which I already had......!) On the Sheds there were only a couple of chap's who'd paid before the company went to the wall.
But Logan are charging a lot more than Emerald or Streamline had previously. If I remember correctly, with Streamline a rating was about £7K as it was done on the 330.