I'm sure at some point I'll have to worry about such things. As it is, I asked my daughter what she wanted for Christmas and she said, "I want a red bear." -Okay, I can do that.
Turns out, red bears aren't as easily sourced as you might think.
But your question is a good and serious one, combatting consumerism is difficult because you cannot shield them from billboards, their friends, the Internet etc. Sure, I can have no TV in the house but it really doesn't matter unless we live in the middle of nowhere.
Values are a real thing though and if your kid sees you valuing material things then chances are they will too. Unfortunately, there comes a time when your kids friends will be as influential to them (or more so) than you are. I guess you have to try and surround them with the right people. -It's going to be a challenge, no doubt about it.