I bought shallot sets from Jung's in Wisconsin about 20 years ago. They no longer have the variety (French Gray shallots) that I bought from them but they still sell shallot sets. See the link below

I also had their golden shallots for many years. My technique is to store all the shallots in my garage over the winter. Whenever we want shallots for the kitchen, they are at hand but we have to stop using them at some point in order to have some to plant. We managed to use all the golden shallots 1 winter, so were only left with the French gray.

Shallots can also be grown from seed. I bought seed for Prisma a few years ago. The resultant sets have done well in reproducing the last 2 seasons and are out there with the French grey in the garden now. I'll try another variety from seed this year.

digitSteve

Here is a link that might be useful: Jung's shallots