simplydiscus.com forum is celebrating it's 13th anniversary next month. I'm a long-time member there.
All of the sponsors on that forum are high quality discus suppliers.
As Star_Rider said, Kenny in Daly City, Ca. is a sponsor there, and is arguably the best supplier of top quality discus in the U.S.
Where are you located anyway, Jack ? - There may be a good supplier near you.
Perhaps I can direct you, depending on where you are.