Certified GKH Gardening Expert
We don't recommend specific places to purchase. What I can recommend is looking to online sources, such as Amazon, Ebay, or Etsy. Alternatively, you can check your local resources for more information.
I can, however, include our article on the care of the tree: https://www.gardeningknowhow.com/houseplants/miracle-berry/miracle-fruit-plant.htm