Wasabi roots are common in Japan and while there are pricing variations, it's not as expensive as its told here.
Plus you can grow them in the US as well (see below).

As far as I understood temperature and water quality were very important, but it seems that isn't that hard to grow some on a pot:
https://www.thespruce.com/growing-wasabi-plants-5082985

In the description says that "You won't be able to harvest the rhizomes of most wasabi plants until the second year", so that's a lot of waiting for it.

TIL even Wasabi is in the brassica family.