Shipping cost will depend on where you live and like the above poster I haven't ordered sudangrass, but I've had good experiences with Welter Seed. It looks like they don't have organic seed for sudangrass, though: <http://www.welterseed.com/ProductTypes.aspx>. They're in Iowa.
LOL... I feel stupid... I just demonstrated how some of us have lost the ability to think and resort to the internet for answers much too quickly. I found this yellow book like thingy with lots of phone numbers in it that the mailman drops off every now and again and I found a place. What makes this worse is that the place I found is where I already purchase my chickenfeed. I'm a dummy... lesson learned.
Time flies like an arrow. Fruit flies like a banana. Steve flies like a tiny ad:
Greenhouse of the Future ebook - now free for a while