very interesting points, James.
It seems that reputation has a lot to do with how easily one can sell either seeds or plants. Looking at the Flourishing Daylilies (Ansari) listings on the fb sales page, it seems that her offerings sell out almost immediately. The prices range from cheap to rather expensive... Counting up on my fingers and toes this morning, it looked like yesterday she may have sold between $800-$1000 worth of plants. And she has been doing it consistently. I believe she grows in pots exclusively, somewhat simplifying the process.
Now, she has a strong following. Some of the others selling through catalogs also have loyal repeat customers and so can count on moving X amount of plants. If you know that, then you can make a business plan.