Further, a younger bird will normally not be as quick to strike out if a stranger approaches. Take note of the environment in which the bird is being kept. Enter the area where the birds are housed and note cleanliness and equipment and the condition of the other birds in that area. Ask for a health guarantee. If the vendor won't give you one, then find a place that will.
Most breeders stand behind and guarantee their chicks.
Evaluate the bird for its health, personality and reaction to you. The first thing to do when looking at a bird is stand back and watch it for a bit before getting close. See how it reacts, how it uses its eyes to watch, if it is really jumpy or more laid back and more or less taking things in stride. Next walk up to the bird to observe the health of the bird and how this bird reacts to you. Without making a move, look at the feet first.