The difference between need and want

Hey, I know it's hard to say no to kids, but we're not doing them any favors by showering them with stuff -- whether it's technology (i.e. iPods) or lessons (private batting classes) or activities (special summer camps, class trips, etc.) Experts are saying that it's not good for our economic health, or theirs, when we succumb to their whining. We should be using that money as parents to protect our future, like saving for retirement.
But like many others I know, it's growing increasingly difficult for me to draw the line. If I don't pay for a special summer program, will he fall behind? If he doesn't go on an expensive class trip or own the latest and greatest, will he feel left out?
I'm battling with this dilemma because my 13-year-old has been whining about getting a cell phone for over a year. All his friends have one, but I don't see the point (or the need) to outfit him with one more tech-gizmo.