Caroline, did you find a scented geranium seed source yet? You mentioned the scented geranium nursery in Nebraska, yes, officially they sell plants, but did you email them about seeds? They might sell you some, they're very nice people.
Scented leaf geraniums are pretty prolific seed setters! The hybrids probably won't come true from seed, but the species will.
There are many herb growers that sell scented leaf geraniums also. It might be worth asking them! You might get a hodgepodge mixture, but
that could be fun!