Instructions
Highlight the hidden advantages of the system. The PS3 can play DVDs and blue ray discs like a traditional disk player. The system also can connect to the Internet and other computers in the house so that your TV can acess the Internet and your hard drive to play pictures and music.
Barter. List tasks you can perform in exchange for the system. Things like painting the house or washing the dog for an extended period are good starting points in the negotiation.
Pay for it out of your allowance. Offer to take a cut every week to offset the purchase price.
Show them the system. Sometimes people need to see and test an item themselves before making the purchase. It is just like test-driving a car. Sometimes the PS3 will simply sell itself if you take your parents to a friend's home or store where they can see how the system functions.
Explain how the PS3 can help doctors to discover cures for certain diseases. You can download a program to the PS3 that uses the gaming systems processor to assist scientists at Stanford University to study the formation of disease in the human body (see Resources below). This can be a major selling point for some parents.