"If any such source exists - which I doubt - I daresay they will charge EBay snowdrop-type prices." I hope no Gerry, this is really dangerous...
Maggy, can I just mentioned something about this crosses. This hybrid has been given many diferent names until we have understood that the localities traditionally idintified as N. cantabricus in fact contained at least 2 species: N. albicans and N. cantabricus subsp. cantabricus. So It was necessary to rename the hybrids with N. triandrus subsp. pallidulus, because all these hybrids were called N. x susannae
The crosses that Mariano del Amo called
N. x litigiosus del Amo, were Narcissus L. triandrus subsp. pallidulus (Graells) Rivas Goday x N. albicans (Haworth) Sprengel, is mantained and the hybrid Narcissus x susannae, which is Narcissus L. triandrus subsp. palliulus (Graells) Rivas Goday x Narcissus cantabricus DC. is redefined as
N. x matritensis Fern. Casas There is only one direcction (at least in Madrid) in N. x matritensis, Ganymedes accting as a mother, and the hybrid has one or more flowers, solitary plants without many vegetative divisions, slender with tall scape, good scent...
In Narcissus x litigiosus, I think there are two direcctions and probably there are fertile clones. We can see clumps with 50 flowers and more, with one flowers short scape, foliosus, and bad scent... and this is because is N. albicans the mother that aport all that characters. It also could have two flowers, because N. albicans (aslo N. cantabricus, N. graellsii, N. rupicola, N. confusus... I think all uniflower narcissi) has a very rare capacity to have a second extra flower. I think Ian showed this capacity and here is an example in N. graellsii
http://www.biodiversidadvirtual.org/herbarium/Narcissus-bulbocodium-L-subsp-graellsii-Webb-KRicht-img8728.html. So Narcissus x litigiosus direction N. albicans could be like this N. graellsii, but in a clump with dozens of bulbs. Here is an example
http://www.biodiversidadvirtual.org/herbarium/Narcissus-x-susannae-FernCasas-img28069.html.
When the direcction in N. x litigiosus is N. triandrus subp. pallidulus the plant is similar to this N. x matritensis (it is wrongly labeled by the admin in this page)
http://www.biodiversidadvirtual.org/herbarium/Narcissus-x-susannae-FernCasas-img62548.html.
Sorry about this long off topic explanation. I don't know any comercial source. I am making N. x litigiosus and N. x matritensis in both directions for my study but I only have capsules setting seeds.