Seeds you get from it this year will still have the genes of all the others it came from, so you could get any number of different crosses from them. I think what you'd have to do is isolate this plant, (pot it up in the fall and give it winter protection so it won't die) then divide it next spring as soon as you see growth starting.
If you can keep it isolated - somewhere far away from any other Rudbeckias, or in a screened cage where bees can't get through to the plants, then some generations down the road, you will have a pure line of seeds, I think. You may have to hand pollinate the plants, too since the bees can't do the job for you.
This is the reason why new hybrids or strains of new plants are expensive at first - the growers have gone through the exhaustive process of isolating the genetic mutation for long enough that it will come true from seed. Or conversely they are simply propagating it by divisions endlessly, which is once again a very slow, laborious process to get to a point of having enough plants to actually market it.
