The ghost orchid is so rare that it has been put on the list of threatened and endangered plants in Florida, one of the few places where it grows. The number of ghost orchids there is around 1,200, and it is illegal to pick any of them from the wild. Since you can't pick them yourself, you're going to need how to buy them, and how to do so within the law.
Determine whether you are up to the challenge of even owning a ghost orchid in the first place. The reason that ghost orchids are so rare in the wild is because they have such a low survival rate--and they have an even lower survival rate in captivity. You're going to need just the right temperature, just the right care, and even then, most ghost orchids will die before growing to their full size.
Find a nursery or garden center that sells ghost orchid seedlings. You will not be able to find full-grown ghost orchids to buy, since nurseries and garden centers take a profit risk trying to grow them. Most nurseries or garden centers that sell ghost orchid seedlings are located in Florida. Call your local nurseries or garden centers ahead of time, since these orchids are rare. Ask if the seedlings can be ordered if they are not in stock.
Search for online orchid dealers if no nursery or garden center near you carries ghost orchid seedlings. Understand that buying online makes growing the ghost orchid even harder, since seedlings may be damaged during shipping.
Prepare an area to grow your ghost orchid before you buy it. The ghost orchid is not a plant you pop in the dirt to grow; it needs a special system designed for its growing needs.