Very useful skill! It seems that selling small amounts of seaberry seed is all the rage on ebay and amazon, but you never know what you are going to get. I thought I would check Alibaba, but that is pretty vague also. I came across this and others like it; Hunjin, Chengse, and Chuyi mentioned. https://www.researchgate.net/publication/311260135_An_elite_variety_of_berry_hippophae_rhamnoides_'Hunjin'
I don't know if there is anyway to find out if there are some landrace varieties or get some seeds from the thornless ones... I'd love to see Hippophae developed into a better agroforestry crop over here.
lots to be gleaned also at http://www.sanddorn.net/index.html
- much of that site is in German.