And now I know...the REST of the story! :)
**For those who do not have the time, the Video is about a Wasabi Grower in Japan. He lives at the bottom of a mountainous valley in Japan. Japanese farmers have developed a method of growing Wasabi in shallow moving water. His family has built a walled area along the streeam that has a sand gravel bottom in which they plant and grow wasabi. They cultivate the stream bottom, set out protective pipe sections in which they plant slips from the mature plants. (It is a lot like growing water cress and t takes 2 years to grow the plant.)
Niche farming: if you have a spring on your property and you can grow water cress in it and it does not get terribly cold I suppose you could grow wasabi (if you can find the plant!) Territorial...when they have it...Sells it for $28 for their slips. The comments at the page for Wasabi at Territorial indicate that most people are treating it like a regular garden plant and fail. If you have a buyer actual wasabi sells for about $100/lb. (Crocus saffron goes for $14,000/Lb! Not sure what Truffles goes for but you can buy small oak trees inoculated with Truffle Mycelium...this would take a while I think!) I think the video gives the best indication of how it could be grown.