Dusty Miller seems to be known in the States as Cineraria, the Latin name, and yes they are available by seed--I grow them every year. They don't flower here until the second year (if I can keep a plant going in the house) but the seeds are so tiny I haven't tried to collect them. Maybe this year!
Your first link is what I know as dusty miller. Also I think you are probably right about the seeds. I don't let mine bloom, and when blooms start I pinch them off. The blooms are not that attractive and I was told by someone somewhere that you are supposed to pinch them off. (Like with Coleus) So unless you are trying to get seeds and let the flowers stay on, of course you would not have seeds... I did not think of that at first when the question was asked.
The whole issue of Dusty Miller is confusing...technically, it's in the family 'Asteraceae', and the genus is 'senecio'--which is often what the seeds are listed under. The species is 'cineraria'. I was quite confused when I received my packet of Silver Dust Dusty Miller the other day from T & M. I'd ordered from their discontinued list, where it was shown as Senecio, but the packet says "Cineraria". So I had to look all of this up. (For some reason, T & M no longer seems to carry Dusty Miller under any of the names.)
The plant most of us know as cineraria is usually grown up here as a house plant, and has very showy flowers.
I rather like the tiny yellow flowers on the Dusty Miller. This is a picture of it in bloom (its second year) very late last season. But for a more formal grouping, it's best to keep the flowers plucked. I like pairing it with deep red salvia.
That IS pretty! I never get that many flowers on it and also they shoot up a long stem with the flowers on it. It has never looked pretty for me. With flowers I mean. I love the silvery foliage which looks good with so many things!
The dark blue accents are simply--lobelia! . Another eye-candy combination is orange dwarf calendula with dark blue lobelia and dusty miller.
My flowers must struggle to grow in my difficult climate (cold nights and variable days) so they all tend to be a bit stunted. It's nice to know that occasionally that's an advantage! But I do envy you people who can grow such lush gardens.
Well, you're right--photos are deceptive! but those really are lobelia. Only other blue I have like that is phacelia, and I didn't grow it last year. It's all in a large canner I use as a planter, so nothing else sneaked in!
This is a picture of the Dusty Miller/Lobelia/Calendula combo I mentioned earlier. I had a 5' row of them, in a 4-tiered planter I have on my deck. The lobelia looks more purple here than it really was.
Dusty Miller starts readily from seed. Mine produce volunteers regularly, and I simply move the babies to wherever I want them. I have created a starting area by throwing piles of deadheaded seeds under the staircase to my 2nd story deck. I have maybe 30 or 40 seedlings growing where there was nothing but the errant weed before.
I have a limited amount of seed I can share, for DG subscribers first. I spread most of it on my property line already -- it simply comes up where I want a Dusty Miller "hedge" -- for me, in a 300-foot long line in front of a row of 2-year-old black willow cuttings, where I want a low maintenance, zero water way of keeping weeds down. Dusty Miller shades out most competitors. Doesn't take out bermuda grass, unforunately -- but not much does!
P.S. My zone 9a is really more zone 8, since the Sacramento Delta gets brutal winds that chill things pretty thoroughly. I am often a full 5 degrees colder than folks in the urban part of Sacramento (and to prove it, I slipped on icy steps last week, and have been enduring puzzled looks from work colleagues who have no experience of icy steps). It's been a while since I was a zone 3 resident, though, so I won't vouch for how Dusty Miller seeds will do where winters are long and cold.