Or similar nonprofit org. A lot of them sell very fair-priced, well-grown seedlings in the spring as a fundraiser. Then you don’t gotta worry about seed germination or a destructive cold snap.
But if you’re looking to grow a lot of flowers, seeds are much more economical — prairie moon nursery is great. Just make sure whatever you order fits your hardiness zone and isn’t overly invasive.
edit: also check your local library for a seed sharing program — free seeds!