Jelitto carries Ammophila arenaria, another member of the American Beach Grass and Dune Grass group.

Here is a link that might be useful: Jelitto

Drake Farms/Edwards Nursery sells both A. Brevigulata and Panicum amarum (another good dune grass).

If you are in a threatened coastal community, you may find your state offers free to cheap plugs and/or seed.

Here is a link that might be useful: Drake farms/Edwards Nursery

Not a threatened community, but a coastal one. Once a year there is a plant sale where they sell cheap Beach Grass and Beach Plums for very low prices. Unfortunately, the sale is in the Spring, and I just found out about it a couple weeks too late.

Why does no one sell it as seed? It's a grass, after all...

According to illinoiswildflowers.info:

"Propagation occurs primarily by dividing clumps of plants and their rhizomes, as most seeds are not viable."