I have 23 this year but am reluctant to give them away to be grafted. They are on one of the gulf islands. I personally did a lot of research and decided to focus on seedlings rather than cultivars. If you urgently need rootstock, one is almost 2 years old with Mammoth cultivar parentage which is most likely way too late ripening for our region unless you put it against a wall.
The round of seeds from last fall were sourced from the earliest ripening fruit from a very large collection. Parents included the cultivars Kaiteri, Kakariki, and Huia and also a couple of unknowns. From the year before I have one remaining Albert's Joy seedling. They have grown easily and quickly from seed for me and none of the ones I planted in ground and left unprotected last (unusually cold) winter died, even the year old saplings. I think there's a lot of potential for them in ground in our region.