Growing Echinacea

I want to grow Echinacea. Does anyone know where I can buy the seeds? Will Echinacea grow in Minnesota, in sandy soil ?

The purple coneflower, or Echinacea purpurea, is one of the easiest medicinal herbs to grow. It is perennial, very hardy, is rarely bothered by pests or disease, and it has a beautiful showy purple flower. And it especially likes sandy soil. Richters carries both seeds and plants.
There are other species of echinacea but the seeds are harder to germinate and plants are slower growing. The narrowleaf echinacea, E. angustifolia, is the species most in demand in the commercial herb industry. We also carry the pale-purple species, E. pallida, which has similar medicinal value.