The average age a pet budgerigar will reach is 7 although many live much longer.
The best age for a pet budgie is 6 to 8 weeks. Some breeders will tell you they are impossible to sex at this age. If they are experienced breeders this will not cause them a problem and they can distinguish cocks from hens quite easily.
A barhead is a general name given to a newly weaned baby budgerigar –at about 6 weeks of age. They are called this because the baby feathers form bar like patterns on the head of the bird. This will disappear when the bird has its first moult and gains it adult plumage – this is at about 12 weeks.
On the Budgerigar Club website there is a directory of breeders that often have birds available. See https://www.budgerigarclub.com/about-budgerigars/pet-breeders-directory/
The best way to catch a bird that has either escaped or is in the aviary or flight is with a catch net. These come in various sizes and are padded to protect the bird.
Once a budgerigar is a few weeks old, you will be able to tell the sex of the bird by looking at its cere (the nostril area). For most varieties, a hen’s is brown, and a cock’s is blue.