I have ordered from Fedco and I trust them, but as Bob said, the probblem is int'l shipping.
springcolor, thanks for that info. I haven't heard of these before. I did some googling and found information on a slightly more reliable source:
http://www.rain-tree.com/yacon...
We also have an empty entry in our database:
Yacon (Smallanthus sonchifolius)
I'm going to research this plant further.