I have to agree with Mary, Seattle area LFS have some great plants if you know where to look. Occasionally A Place for Pets in Burien has Java Fern 'Trident' and Pogostemon erectus. At Sierra Fish and Pets in Renton they regularly have Nymphoides sp 'Taiwan' and occasionally they have Hygrophila pinnatifida.
Robert may have to make a trip up to Seattle and do some scouting; the selection of aquatic plants in Seattle has changed substantially in the last few years!
75 Gallon, 2X55W AH Supply CF 8800K, 1XMarineland Doublebright, 2X Marineland 350 Magnum; 45 Gallon Tall, 96Watt AH Supply CF 6700K; 30 Gallon Long; 2X36W AH Supply CF 6700K; 20 Gallon, 1X26W AH Supply LED kit; all with Press. CO2; (Calcined) Montmorillonite Clay
Greater Seattle Aquarium Society (GSAS)