There is no limit at the present time here in Australia. To show birds it costs $0.50 per entry. Some breeders show 20 - 30 birds at each show (or more).

However, you can only enter in one class e.g. Novice. You can enter as many divisions as you like and show more than one bird in each division.

In Australia these divisions are determined by the Australian National Budgerigar Council. These are some of the divisions:

Normal Green (except grey green)
Normal Grey Green
Normal Blue (Except grey)
Normal Grey
Black Eyed Self
Lutino
Albino
Greywing
Cinnamonwing
Clearbody
Lacewing
Clearwing
Recessive Pied
Saddleback
Crested
Yellow Faced Blue
Fallow
Dominant Pied

There are several more divisions - as outlined in the ANBC publication "The Standard", which is available through local budgerigar clubs