You might try that. Check with the dealers in your area. They might not be willing to part with big mature roots unless you pay a hefty price, but you might easily convince them to sell you some smaller or less desirably shaped (pencils) roots which might be mature enough to produce seed next fall.
Short of that or hunting some of your own, get some seed and nurse them through. I've got seed on 2 year plants in one of my beds this year. Go figure.