I just saw this today. Fairchild Tropical Botanic Garden in Coral Gables, just south of Miami.
[url]http://www.fairchildgarden.org/Events/?date=03-2011&eventID=418[/url]
They say 50 vendors, but they don't have a list.
Fairchild's 9th Annual International
Orchid Festival
Friday, Saturday and Sunday, March 11, 12, and 13,
9:30 a.m. - 4:30 p.m.
The world's most coveted plant comes to Fairchild in all its forms, colors, fragrances and splendor. Orchid vendors from around the world will converge on Fairchild to sell, discuss and display thousands of orchids in every shape and size. Visit the Orchid Tea Room from 11:00 a.m. – 3:00 p.m. to relax, then stroll through acres of orchids, food vendors and orchid supplies.