You can buy the real plant at stores like Lowe's. Any store with a decent nursery should have Salvia. A local nursery would be a great bet too.
If you are expecting to smoke the leaves, don't get your hopes up. Just smoking leaves directly off the plant (with no extractions) only tastes awful and does not make you trip. In order to get enough to smoke, you would have to buy SEVERAL plants and extract the psychoactive.
If you want them just for aesthetics, then go for it. Don't expect a great experience smoking the leaves from a plant that you got at Lowe's though.