Yes I have started sea buckthorn from seeds. In my climate it takes 3-4 years till they produce fruit. Starting them from seeds will produce a lot of male plants, end every bush will be genetically different, end because of you're cold climate a lot will die ... but starting 400000 plants is easy and if you are left with 100000 it is still cheaper than buying them.
In august we will harvest the berries in Romania if you want I can send you a couple of kilograms of seed.
In the next weeks i'm going to make a article about germinating the seeds.