Hemianthus Micranthemoides sold anywhere?

I've been trying to find a place that sells Hemianthus Micranthemoides
(preferably by mail) for a while now without success. I've checked the
Aquatic Greenhouse and Aquarium Driftwood sites and neither has it. I've
tried calling Delaware Aquatic Imports but haven't gotten a hold of the owner
yet. Does anyone know of a source, or is this particular plant generally not
available and/or difficult to care for?