Bear Farm Yarns
Ridiculously good prices on wool yarn. I'm psyched. As soon as I let myself off my yarn diet, I'm raiding their store. I don't see offers for tours or anything, though the farm is only about 2 hours away.
Bendigo Woollen Mills
More variety in the fibers offered at Bendigo. They're in Australia, so shipping would take a while. But I did a calculation, and found that even with shipping, the price of the yarn, when converted to USD, turns out to be a real deal! Also, they're endorsed by the Sticks & String podcast.