I began my study of Sai in 1978 when Charles Murray taught me Chantan Yara No Sai, my first kobudo kata.
He had studied it in Agena in 1972, under Shimabuku Tatsuo and his son Shinso. I suspect he taught me it first so he had someone to work out with.
When he told me to first get some Sai, I was able to do so when on a business trip to Philadelphia. I went to the old location of Asian World on N. Broad Street. Then I purchased a Bo and a set of Sai. The Sai were Chromed Steel, fairly balanced but not perfect.They are still the sai I have used to this day.
Then sweat equity for several decades. Hours and hours working sai during that time.
Long before I heard of the idea of perfectly balanced Sai. I had no interest in obtaining such sai.
What I had discovered is that the Sai through long practice become perfect in your hands because you shape yourself during the practice to make them perfect in your hands. I see no need to give confidence to another in their existancs. Though not necessarily perfect Sai, you make them perfect for you.
Now Sai are no longer necessary for self defense, Attacks with swords are not likely. Of course their purpose is very necessary because of the force enhancement the training provides.
But why do you need perfectly balanced Sai? At one level the last thing I would want is to have my sai be perfectly balanced in another’s hands.
Of course it is your business should you want to get such a Sai, it does not change the decades of work you will need to make them perfect for you.