Take care when selecting a parrot. Look for brave, clear-eyed individuals, with firm droppings. Listen to the dealer's experience with that particular bird, and don't be afraid to ask candid questions about current behavior and what the bird might be like as an adult. Expect some sort of guarantee, and try to have the bird examined by an avian veterinarian as quickly as possible. Buying a parrot on impulse without the proper background and information can spell disaster.
For more information, read
How to Pick the Perfect Parrot.