Might try the Pike's Nursery on Roswell Rd in Buckhead. They are a Monrovia Nurseries retailer and should have it or can order it for you.
Other cultivars that are hardy in the Atlanta area, are 'Mystery', 'Aimee' or 'Aimee Yoshioka'.and others.

You might inquire if the plants are grafted or cutting grown. The grafted one's usually cost more, but are not as susceptible to nematode damage.
Rb

I would not recommend planting a grafted gardenia outdoors in Zone 7B. There are winters in Zone 7B and higher during which gardenias are frozen to the ground. When this happens, most gardenias rebound by regenerating new growth from their root systems. If the gardenia is growing on its own roots, it will come back true to its variety. However, if the gardenia is grafted and killed to the ground, it will come back as the variety of the understock. Therefore, one should buy an "own-root" gardenia, not a grafted one.

A good, reliable mail order source of the 'Chuck Hayes' gardenia is Niche Gardens in Chapel Hill. Contact information follows: Niche Gardens, 1111 Dawson Road, Chapel Hill, NC, 27516; (919) 967-0078, Phone; (919) 967-4026, FAX; mail@nichegardens.com, e-mail; http://www.nichegardens.com, URL.

The Gardenia jasminoides 'Chuck Hayes' is said to be hardy down to -5°F (-20°C), with minimal damage. by comparison, G.j. 'Mystery' exhibited approximately the same amount of damage at 0°F (-18°C).
My 30+ years old, no name Gardenia jasminoides survived 2 successive nights of -12°F (-24°C) during January of 1985, with only minimal damage. Only the low growing 'Radicans' were affected and had to be cut back to the ground. All have survived temperatures a few degrees below Zero, with only slight damage.

Someone should tell the folks at Niche Gardens that Gardenia jasminoides 'Chuck Hayes' is not a hybrid, as indicated in their catalog. It is a seedling selection from the UVA Experiment Station, Hampton Roads, VA (See PP08755)
Rb

Here is a link that might be useful: PP08755

Year before last, most parts of South Carolina experienced a devasting Easter Freeze, striking while the azaleas were in bloom and the sap risen in native and exotic plants. New oak leaves were blackened by this late freeze. What I'm getting around to saying here is that the Easter Freeze, which was in the low twenties or maybe the upper teens (I've forgotten the exact temperature), killed our fairly large 'Chuck Hayes' gardenia outright and damaged such cold-hardy gardenia cultivars as 'August Beauty' and 'Kleim's Hardy.' Our two 'August Beauty' gardenias and the 'Kleim's Hardy' are on the way to recovery after considerable pruning. And there is a scrawny little 'Chuck Hayes' gardenia in another part of the yard that barely escaped total destruction by the Easter Freeze. (It is, however, pitiful and should probably be put out of its misery or resurrected, one or the other.) I plan to replace the 'Chuck Hayes' gardenia with one from Niche Gardens sometime in mid- to late spring but hope to plant it in the foundation shrubbery, where it will be more sheltered, instead of planting it in the exposed location occupied by its frozen predecessor. Oddly enough, our two old-fashioned, generic Cape jessamines, aka gardenias, were virtually unhurt by the Easter Freeze; but they are sheltered by a pine canopy, which probably kept them a few degrees warmer than their named-variety cousins.