I currently have only three parakeets, I had five but lost my best two birds (figures, huh?). I plan on getting several more pairs to breed later on.
Parakeets are an afforadable bird, they range anywhere from $7.00 to $12.00 but in all truth they are quite loud and very messy, and for such a small bird they can have a vicious bite. Be forwarned, once they bite they don't like to let go.
Parakeets can be trained, but usually only if you keep a single bird. It is also said that the male can learn to talk. This all depends on the individual bird though. You can tell the male parakeet from the blue band of skin above his beak, where the female's is brownish in color. Most, but not all young parakeets have the same color nose band, male or female, until they mature. They live an estimated ten years depending on the health of the bird and of course how well you care for it.
They eat seeds, fruit, millet sprays, and veggies. Fresh water should be made available daily. If their water container is not enclosed you should change the water every day, sometimes more often depending on just how messy your bird is. There are also vitimian drops that can be added to the birds food and water. They also need a container of grit and a cuttle bone. The grit aides in the digestion of their food, and the cuttle bone helps keep their beaks from over growing. Their claws grow constantly and need to be clipped from time to time. If you don't want to do this, or aren't sure how to do it, most pet stores will gladly do it for you. The same goes for clipping their wings.
Parakeets are a fun bird to have but not one that I would advise as a pet for a small child.