Purchase of plants
I have tried to find Heliotrope plants in my city. No luck.
They may be hard to find in your area because they are not considered hardy there, neither are they considered a houseplant; also, they're sort of "out of fashion." However, you can order them online; just search "where to buy heliotrope flowers." This article has information you should check out before you start these lovely plants: https://www.gardeningknowhow.com/ornamental/flowers/heliotrope/growing-heliotrope-plants.htm