Parakeets also get a lot of exercise by climbing on the bars. Make sure that the bars of the cage are close enough together, so that the bird can't fly out or even stick its head out. If your pet sticks its head out through the bars, it might get its neck caught and choke to death. Today's modern cages are made of metal and plastic. Don't put parakeets in a wicker or bamboo cage.
Cages come in every color of the rainbow.
The color is your own personal decision - buy what you like and what matches your home decor. The color of the cage makes no difference to the birds. Be sure that the birds' water and cage is clean. The birds should be flying and climbing about their cage, making quite a bit of noise. If the birds are very quiet and tend to sit in one spot, then go to another store.