Most of the bamboos that I have ever sold are the moso seedlings which were either planted in spring of 2009, or 2010. I have either traded away, given to people or sold all but 1 of the ones from the 2009 batch which I plan on keeping to see how it does. Moso seems to excel especially in a warmer climate(zone 8 & warmer) so I have gotten emails back of reported results that would never happen up here simply because the growing season is not long enough, and it doesn't get hot enough in the summer to maximize their potential, not to mention the inevitable die back since I haven't figured out how to protect them completely until last winter.
Here are some of the Moso bamboos that were sold over last year.
These are the big ones that have rhizomes running up to 1-2ft and were very difficult to fit into a large flat rate box, even with a lot of the soil shaken out.
The smaller ones usually in 2-3 gallon sized pots usually had much less rhizome growth, and since I use a very light self-made potting mix, I usually shake it out to re-use. I often used gallon jugs to give an idea of the size for ebay posts. These usually required medium flat rate boxes, and all my plants are shipped priority mail, and drenched in rooting hormone to reduce transplant stress. They are packed tight to the box to avoid movement which can usually be done because they wouldn't fit into these boxes if I didn't shake off any soil.