A normal rhizome is 4-6 inches with a few buds already present. I may have gotten a bundle for cheap, $1.25 a root, some being the same as the average rhizome, some being much better. Just consider a normal root is $4-$6. There may be 2 roots of the 12 that did not show any bud growth when I received them. They will just take more time. Other's are vigorous growers. I would not go with buying a bundle of 50 roots that are 2" each. That would defintelty take a few years to grow up good, but once it did the yield would be crazy.
The basic thing is the more roots the rhizome already has established the better the plant will be at producing flowers for the first year. If you want to spend more money on "jumbo" roots and such you can and will have a better yield that first year. If you can afford it you can have a lot of varieties in jumbo form. Planting 2 normal rhizomes per hill can also help out your yield.
There is a nice pic of a 3 year old centennial hop root that is 3 feet across. That just tells you how much an original rhizome grows in that amount of time.