You can go to college road, but shud avoid this moonsoon season for there are lots of diseases emerging in this season in birds.
Also, you can get birds from Sunday Bazar's poultry section on almost the same rates in Peshawar Moor, Islamabad that is held on tuesday and friday as well.
For kids or new hobbiest, australian parrots (also called budgies) are good to start with. They are hardy, need less space (small cage for a pair ) very colourful, easy breeder, commonly known and less expensive. You can get a good pair between 300-400 rupees.
For green parrot, that Naweed mentioned, the price is 300-400 for a chick that is handfed. This is common green ringneck that is local bird, but the chick can be tammed to talk.
My advice, if kids are too young or not knowledgable about birds or are seasonal hobbiest and not enthusiast, you should avoid keeping birds for them as they are living beings and require lots of daily care for feeding and clean up etc. Your carelessness can kill/hurt a living creature.