You'll find several places that sell the seeds of this plant, on line.

I have two plants which I grew from the seed my two Horizon Herbs plants produced. Originally there were three but I shared one with an Amish neighbor who had a greenhouse and better growing conditions. She is moving to Michigan so I won't learn.
Now, I believe they can be started with cuttings from my plants. I just took a few cuttings today and will get back to you if you request on this. I am willing to share if it is possible to mail the plants and not too costly.
Later, Marilyn