I may well have a few spare B filifolia seeds, if it is legal to ship them from the UK to the US. I am about to sow some of my seeds- if you PM me in about 1 week, I will tell you if there are any left (if not, I will certainly have some later in the season- my plants produce abundant seed when cross pollinated). If so, you can have some for nothing. I am also hoping to have some B gigantea seeds later on the season. I have just pollinated my plants, and they take several months to produce seeds. You will need GA3 to successfully germinate these species. I have successfully used it with B filifolia, lamellata (a very close relative of B gigantea), and B rorida, and am about to try with B aquatica- it does work!
Cheers,
Greg