Salvia Divinorum is species of sage that has purported psychoactive effects and has been used for shamanic purposes in Oaxaca, Mexico, for hundreds of years. Salvia is a cultivar, meaning it is a species that has been bred by humans and as such is relatively easy to care for as a houseplant. However, finding a live Salvia plant presents a challenge as many nurseries are unfamiliar with this species and it may be illegal in your state.
The best place to buy Salvia Divinorum plants is on the Internet. Many websites that specialize in psychoactive plant substances, or entheogens, also sell live Salvia plants. Most online retailers of Salvia plants sell small potted specimens that have been propagated from clipping off of larger plants. Since the larger the plant the higher the chance of survival, do some comparison shopping to see which company sells the largest. Always check to see if it is legal to ship Salvia to your state or country before placing an online order; many vendors do not offer refunds on misplaced orders and will not ship illegally.
Some specialty nurseries do carry salvia divinorum plants. Your best bet is to find a nursery that specializes in medicinal plants or exotic plants form Latin America. Call before you visit and make sure you ask specifically for "Salvia Divinorum," as Salvia denotes a large genus that contains many different types of sage plants, many of which are very common. Always check out the health of the live plant if you can; a healthy Salvia plant should have large emerald green leaves and sturdy square stems.
Many stores that carry supplies intended for use in growing indoor marijuana, such as grow lights and bat guano, also carry live Salvia plants. Growing marijuana is only legal in states that allow cultivation for medicinal purposes, so many grow stores do not advertise themselves as such. Salvia plants grow very well under the same grow lights intended for marijuana cultivations and some grow stores have taken to growing Salvia under them as a display.
Many large garden centers and botanical societies have annual and quarterly sales. If you attend one, ask around; you are sure to find someone who is growing Salvia divinorum and will sell you a clipping.