CONECA are the experts. They post lists and price guides and certify varieties. I'm not as sharp eyed as I used to be so I'm leaning to it being an RPM. Wexler is one of the experts on those and has published several books. I don't think that there are any RPM varieties worth more than what a TPG would charge. I'm not up on current CONECA prices to certify but I think it would be less than TPG companies. It would also be more accurate. good luck.