Most main stream pet shops will sell a wide range of budgerigars, or you may be able to source them from a local breeder, you can look for adverts in the newspaper, bird magazines or even online. Take all the time you need when choosing a budgerigar, look out for budgies that are active and lively and show an interest in you when you approach the cage or aviary. The breeder or shop assistant should be able to tell you whether the budgie is a cock or a hen.
The younger the budgie the better, a bird that is 6 months old will be hard to tame, if they tame at all. The best age is around 6 weeks old so they build up trust and interact with you from a very young age. Sometime the person selling the bird will try to sell you an older bird with the excuse of it being tamed already, this is for you to judge. You can roughly predict the age of budgerigars by looking at its beak, if the bird is under 3 months old its cere (directly above the beak) is light pink in colour, when they grow into adult this patterns a blue or brown colour. Some young budgerigars have the stripy markings on their head extend all the way dawn to the cere, this usually disappears after they first moult at 3 months old.
Both sexes of budgerigars make very good pets. You can keep 2 cocks and 2 hens in the same cage together, you can keep 1 hen and 1 or 2 cocks in the cage together, but you must never keep 2 hens and just 1 cock together as the hens will fight each other.
You can tell the health of the bird by looking at their feathers, they should be smooth and sleek, and their feathers should only be fluffed up if they are sleeping. Look for kinks and bends in the tail feathers, they should be straight not at an angle. Its cere should be without crustiness and clean and its chest should be well rounded, not hollow. Check the eyes of the budgie, they should be bright and alert and they should breath with their beak closed.