How can parents help children handle peer pressure?

Recently two of my friend s wore 3/4th Palazzo in kitty party which I liked very much and hunted for it and bought two. Being an adult when I can't control peer pressure then how can kids do. peer pressure is common among children. My eight year old son whenever sees some new pen with his friends in the school comes home and asks for the same. He is so stubborn that some how he pressurises his papa and finally buys it. Making children understand that peer pressure should be avoided is very difficult. We should make them understand that it's not a good thing. If this behaviour continues it goes on to adult stage and then it will be very difficult to change at that age. I keep on telling my children that they should be self satisfied and should not get attracted What others have. It will not take them anywhere. Others have what they need and we should buy only what we need and should not waste money. This advice has brought much change in them and hope to see many more changes in them.