GordonRichards might have some. I was going to buy a small quantity from him but didn't catch up with him again. They usually have it at sweetaquatics.com too.
C. ciliata is also a great choice for brackish ripariums. Its native habitats include estuaries with brackish water.
It tends to grow up pretty fast and it also flops over with the weight of the heavy leaves. I recommend planting two or three in each planter so that it will grow more bushy. C. ciliata is another "heavy root-feeder" and will also grow best if you put some topsoil in the planter.